- British hardened field defences of World War II
British hardened field defences of World War II were small fortified structures constructed as a part of British anti-invasion preparations. They were popularly known as pillboxes by reference to their shape.
Design and development
In May 1940, the directorate of Fortifications and Works (FW3) was set up at the War Office under the direction of Major-General G. B. O. Taylor. Its purpose was to provide a number of basic pillbox designs which could be constructed by soldiers and local labour at appropriate defensive locations. In the following June and July FW3 issued 6 basic designs for rifle and light machine gun, designated Type 22 to Type 27. In addition, there were designs for gun emplacements suitable for either the Ordnance QF 2 pounder or the Hotchkiss 6pdr gun (designated Type 28) and a design for a hardened medium machine gun emplacement.
There were also designs for pillbox-like structures for various purposes including light anti-aircraft positions, observation posts and searchlight positions to illuminate the shoreline. In addition, the Air Ministry provided designs of fortifications intended to protect airfields from troops landing or parachuting. These would not be expected to face heavy weapons so that the degree of protection was less and there was more emphasis on all-round visibility and sweeping fields of fire. Many of these were later reinforced.
Embrasures were available precast and factory produced to standard designs, but as these were in short supply some embrasures were improvised from brick or concrete paving. Embrasures were frequently fitted with a steel or concrete-asbestos shutter. From March 1941, some pillbox embrasures were fitted with a Turnbull mount: this was a metal frame that supported a medium machine gun.
The degree of protection offered by a pillbox varied considerably: the thickness of the walls and roof generally varied from just 12 in to 3 ft 6 in (0.3 to 1.1m) or more although the commercially produced designs were often much thinner. In March 1940, General Brooke carried out penetration trials and recorded that a 25 mm anti-tank gun could easily penetrate up to 2 feet (60 cm) of reinforced concrete. Despite such results the thick-walled pillboxes were designated as shell-proof, whereas the thinner-walled pillboxes were designated as bulletproof.
Internally, pillboxes are generally cramped and spartan. Some internal concrete shelves and tables were provided to support weapons and some were whitewashed inside. Only the Type 28s provided a little space — sufficient for a few home comforts.
The basic designs were adapted to local circumstances and available building materials such that, outwardly, two pillboxes of the same basic design could look quite different. The height of a pillbox could vary significantly according to local needs: some were half buried so that the embrasures might be as low as ground level, others were raised up to give a better view; those built into hillsides might lack embrasures on some walls; the entrance could be moved and its size varied as might be convenient and there may be additional walls to protect the entrance, a freestanding blast wall or a steel door.
Appearance also varied due to the building materials used, although all the FW3 designs are formed from reinforced concrete. Where brick was used as a shuttering, the bricks essentially formed a mould into which concrete was poured, the bricks being left in place. Otherwise, the pillbox was formed using shuttering of wood (usually planks, but sometimes plywood) and/or corrugated iron. Wood shuttering was removed, whereas corrugated iron was sometimes left in place. Construction often took advantage of whatever materials were available locally (for example, at the coast, beach sand and pebbles would be used) and this expedient use of local materials had the added advantage of aiding camouflage. The reinforced concrete used in construction was generally conventional making use of thin steel rebars with floor, walls and roof all mutually bonded. However, several instances are known where scrap metal had been used such as parts of an old bed or park railings.
Local commanders introduced modifications to the standard FW3 designs or introduced designs of their own which may be produced in some numbers or completely ad hoc designs suited to local conditions. Other designs were produced as commercial ventures. Finally, there were a small number of pillboxes that had been constructed in the first world war.
FW3 pillbox types
The approximate numbers of extant pillboxes of each type are given based on data from the Defence of Britain database.
The type 22 pillbox is a regular hexagon in plan with an embrasure in five of the sides and an entrance in the other. The embrasures are suitable for rifles or light machine guns. Some have a low entrance that allows an extra embrasure above. Each wall is about 6 feet (1.8 m) long and it was generally built to the bulletproof standard of 12 inches (30 cm) thick, although 'tank-gun proof' versions with walls around 40 inches (1.0 m) thick were also built (e.g. the granite and concrete examples on the Cowie Line in Kincardineshire). Internally there is a Y- or T- shaped anti-ricochet wall (the top of the Y/T nearest the entrance), the internal wall also helps support the roof.
The type 22 is the second most common pillbox type with 1,209 recorded as being extant. It is easily confused with the common type 24 which is an irregular hexagon and the less common octagonal.
The type 23 pillbox is rectangular in plan — essentially two squares, one of which is roofed and the other open — with embrasures in each of the available sides of the covered section. The embrasures are suitable for rifles or light machine guns. The open section was for a light anti-aircraft defence: a Bren or Lewis gun on a mounting. Usually, there is no ground level entrance, to get in one had to climb over the wall into the open section and then pass though a door to the covered section. The walls were 8 feet (2.4 m) wide by 16 feet (4.9 m) long and usually built to a bulletproof standard of 12 inches (30 cm) thick.
The type 23 is uncommon, 156 are recorded as being extant. A further variant exists in Lincolnshire consisting of a double chambered type 23 with an access door with anti-aircraft gun mount and a chamber on either side
The type 24 pillbox is an irregular hexagon in plan. The rear wall is the longest at about 14 feet (4.3 m), this has the entrance with an embrasure on either side. The other walls vary from 7-8 feet (2.2-2.5 m) each having a single embrasure. The embrasures are suitable for rifles or light machine guns. Internally there is a Y shaped anti-ricochet wall (the top of the Y nearest the entrance), the internal wall also helps support the roof. The type 24 was always built to at least bullet-proof standard of 12 inches (30 cm) thick, but often was thicker.
A thick walled variant was introduced to a shellproof standard; it was larger externally and had walls 36-50 inches (91-127 cm), thick. (This thick-walled variant is, confusingly, sometimes called a Type 29 by pillbox researchers, but this is not an official designation and should be avoided.) In a variant on the Scottish Command Line the entrance was moved from the long wall and the two rifle embrasures were increased in size to allow a Bren and Boys Anti-tank rifle to be mounted side by side.
The type 24 is the most common type with more than 1787 recorded as being extant.
The type 25 pillbox is the only FW3 design that is circular with a diameter of 8 feet (2.4 m). The walls were just 12 inches (30 cm) thick with no internal walls. There were three embrasures suitable for rifles or light machine guns and a small entrance like a low window. This design was made from reinforced concrete shuttered by corrugated iron; this gave the design the popular name Armco after the manufacturer of corrugated iron of that name.
The type 25 is rare, about 46 are recorded as extant.
The type 26 is a simple square in plan, each wall being 10 feet (3 m) long. There is a door in one side and embrasures in each of the remaining three walls with, possibly, an additional embrasure next to the door. There are no internal walls. Occasionally, there are two embrasures in one of the walls. The embrasures are suitable for rifles or light machine guns. Walls are normally constructed to bulletproof standard at about 18 inches (46 cm) thick.
The type 26 also had an important prefabricated variant, the shuttering — both inside and out — was provided by precast concrete slabs slotted into reinforced concrete posts. The shuttering was filled with concrete in situ. This pillbox was also known as the 'Stent' after the company that produced the prefabricated components, Stent Precast Concrete Limited. On those examples where damage allows inspection of the construction, it seems that the concrete fill was not reinforced.
The type 26 is uncommon, 199 are recorded as extant.
The type 27 is the most varied of the FW3 designs, it may be an octagonal or hexagonal in plan with walls between 9 ft 9 in and 11 ft 6 in (3.0–3.5 m). The outer walls being 36 inches (91 cm) thick and have embrasures suitable for rifles or light machine guns on each facet. Its defining characteristic is a central well open to the sky that could be used as a light anti-aircraft position.
Type 27 is uncommon, 127 are recorded as extant.
The type 28 is the largest of the FW3 designs and the only one with a specific anti-tank capability. It is almost square in plan with the forward facing corners chamfered. The walls are about 20 by 19 feet (6.1 by 5.8 m) long constructed to shell-proof specification at about 42 inches (107 cm) thick. There is a very large forward embrasure. It was designed to take an 2 pounder anti-tank gun or a Hotchkiss 6pdr gun. The gun shield of the artillery piece would largely fill the aperture. There are usually embrasures suitable for rifles or light machine guns in each of the two side walls.
Superficially, the type 28 resembles the smaller Vickers MMG emplacement, but the aperture is much larger and there is a very large rear entrance designed for ease of wheeling the gun in and out.
The type 28A is an important and common variant – it is more common than the unmodified type 28. It is wider than the type 28 to allow for a side area for an infantry chamber giving a forward facing embrasure suitable for a rifle or light machine gun. This resolved the problem of the type 28 being vulnerable to a head-on infantry attack.
A further, rare, variant is the type 28A twin, which has two main gun embrasures on adjacent walls giving two possible firing positions for the one main gun together with two adjacent infantry chambers.
The traverse of the gun was limited to about 60°. Generally, these pillboxes were positioned to fire along fixed lines, such as enfilading fire across an anti-tank ditch or at a bridge and in such positions the limited traverse of the gun creates no real disadvantage; whereas, the small size of the embrasure provides greater protection for the gun and its crew.
The type 28 and its variants are fairly common, there are some 350 or so recorded as extant.
Vickers MMG emplacement
The Vickers machine gun pillbox is essentially square in plan with the forward facing corners chamfered. The walls are 14 feet (4.3 m) long and there is generally a freestanding blast wall covering the entrance on either the left or right side. The walls were constructed to shellproof standard of 36 inches (91 cm). There are no internal walls. There is a large embrasure and inside is a concrete, trapezoidal table on which to mount the weapon's tripod. The other walls would each have an embrasure suitable for a rifle or light machine gun.
They are frequently sited in pairs and were often dug-in with overhead earth cover.
Vickers MMG emplacements of this exact type are uncommon, just over 75 are recorded as extant but there are many local variants of this basic type.
Other hardened defences
Field gun emplacements
There were a wide variety of field gun emplacements, most resembled larger version of the Type 28 pillbox.
The Cantilever or Mushroom pillbox was designed and constructed by F C Construction for airfield defence. The cantilevered design allowed a 360 degree embrasure for all round defence against air landed troops at the expense of some protection. The central pillar acts as an anti ricochet wall. Weapons were mounted on a tubular rail for 360 degree traverse.
The lozenge pillbox is found only in the North East of England. Lozenge pillboxes are an irregular hexagon in plan with the front and rear walls significantly longer than the others, this allows space for four forward-facing embrasures. The rear wall has two embrasures and an entrance. The four short walls each have a single embrasure. Internally, an anti-ricochet wall runs longitudinally. It was designed for infantry armed with rifles and/or light machine guns.
The eared pillbox is, like the lozenge pillbox, found only in the North East of England and has an irregular hexagon plan. There are two large embrasures intended for medium machine guns. There is a bulge at the base of the wall below the embrasures that is thought to have accommodated the cooling system for the machine gun. Internally, there is a short anti-ricochet wall.
The two embrasures are at 90° to each other giving an arc of fire of about 180° with no way to direct fire behind the pillbox. This design is frequently found on or near beaches — ideal for providing enfilading fire. There are two entrances with openings in the same direction as the embrasures.
Found only in Lincolnshire, this type has become known as a Lincolnshire three-bay pillbox. It is essentially a modification of the FW3 type 23 having an open light anti-aircraft position in the centre and fully enclosed bays at either end.
The Dover Quad pillbox is a 13 feet (4.0 m) square pillbox with wide embrasures and an overhanging roof slab. This design is only found in the Dover area of England and are very often found at high commanding positions. Some commentators opine that the Dover Quad is a poor design: the overhanging slab, while offering some protection from strafing, is liable to ricochet bullets from below into the embrasure which is, in any case, wide giving inadequate protection. Given the vulnerability of the port of Dover, it is possible that these were among the first World War II pillboxes constructed and they may have pre-dated the FW3 designs, but there is no evidence for this.
Section post / Seagull trench
Section posts are essentially hardened trench works. Constructed to bulletproof standard, occasionally without a roof, they are long and have a large number of embrasures. Shelves of wood or concrete are fitted below the embrasures in the principal direction. A specific sub-type of the section post is the Seagull trench named for its W shaped plan view like a Seagulls wings. These are predominantly found at airfields.
Somerset defence post
The defence post is only found in Somerset; it is about 8 feet (2.4 m) square with walls about 15 inches (38 cm) thick and has wide slits extending the full width of three faces. There is a porch covering the entrance. Some have an open section on top reached by rungs and a ladder.
The Norcon was a small circular pillbox named after the company that manufactured it as a private commercial venture. It was made from a concrete pipe 6 feet (1.8 m) in diameter and 4 feet (1.2 m) high; the walls were 4 inches (10 cm) of non-reinforced concrete with several cut loopholes. It was described as being possibly the most dangerous, cheap and nasty of all the pillbox designs. Being quick to manufacture was its biggest asset: it was possible to turn out about 20 a day, the concrete being cured in about 24 hours, but few were actually built. The standard model lacked a roof: others had a roof made of timber and corrugated iron, and earth; extra protection was provided by the use of sandbags.
Ruck machine gun post/pillbox
The Ruck machine gun post (or Ruck pillbox)was designed by James Ruck and was made from prefabricated sections, paving slabs, sandbags and rammed earth. The Ruck machine gun post was relatively widely used in Lincolnshire and along the east coast of England, but is now extremely rare with just a handful of extant examples. Five Ruck machine gun post sites are recorded in the Defence of Britain database.
The need to defend airfields presented special problems. Airfields were large open areas where any above-ground structure would present a hazard to aircraft. One solution was the Pickett-Hamilton Fort, this was designed to be lowered to ground level while aircraft were operating, but to be raised when necessary by means of a hydraulic mechanism. The fort was manned by a crew of two with light machine guns. Access was provided by means of a hatch in the roof. The forts were prone to flooding and they were not sufficiently strong to bear the weight of the heavy aircraft developed during the war.
Allan Williams Turret
Pillbox formed by a metal turret, which could be rotated through a full 360 degrees, set above a steel and brick-lined pit. It was designed for a machine gun to be fired either through the front loophole which was further protected by shutters, or through the circular opening in the roof in a light anti-aircraft role. According to the manufacturer, it was suitable for Vickers, Bren, Hotchkiss or Lewis machine guns in either a ground defence or anti-aircraft role, or a Boys anti-tank rifle or rifle grenade for ground defence. Weapon change requires selection of appropriate bracket. The army did not favour the design, most were installed at airfields.
The turret was designed by A.H. Williams in conjunction with Colonel V.T.R. Ford and Lieutent Williamson. Williams was the Managing Director of Rustproof Metal Windows Company in Saltney, Chester where the turrets were produced. The company had been engaged in war work since 1939, mainly manufacturing ammunition boxes for the Admiralty using a patented galvanising process.
The turret had a garrison of two men or, if necessary three men, for whom there were folding seats inside. One man can rotate the cupola which is on roller bearings and requires 15 lb of force to move it.
The Tett turret was named after its inventor H.L. Tett and manufactured as a private commercial venture by Burbridge Builders Ltd of Surrey. It comprised a revolving concrete turret mounted on a ball race that allowed it to be turned easily. The turret was set above a pit; in early designs, the pit was formed by a standard section of concrete pipe 4 feet (1.2 m) in diameter.
Today, extant examples are very rare.
Spigot mortar emplacement
A spigot mortar emplacement was unroofed, sometimes constructed of brick or concrete, but may be a simple revetted earthwork. Its defining characteristic is a central concrete pedestal with a stainless steel peg (rust free even after more than 60 years). The pedestal was for a type of spigot mortar called the Blacker Bombard — effective against both tanks and personnel — at ranges of about 100 yards (90 m) and 500 yards (460 m) respectively.
Embrasured walls and buildings
Existing walls and building provided a ready-made alternative to a pillbox. Whatever may be lacking in protection was made up for by speed and convenience.
Detailed instructions were given for the careful concealment of pillboxes and other field defences and all pillboxes would have been camouflaged. Many were dug into the ground or inserted into a hedgerow or hillside to provide the lowest possible profile; others had soil piled up on the roof and sides. Camouflage paint schemes and camouflage netting would be used to help break up the outline. Use was made of local materials: concrete made with beach sand, a covering of beach pebbles, or stone from a nearby cliff was not only a time saving measure but aided camouflage by helping the defences to merge into the background.
Artists such as Roland Penrose (author of the Home Guard Manual of Camouflage), Stanley William Hayter, Julian Trevelyan and many others were employed to conceal defences. In built-up areas pillboxes were disguised to look like a part of an adjacent building, carefully matched and provided with a roof to look as if they had always been there. In extreme cases, they were built inside existing buildings.
Some pillboxes were carefully constructed to resemble a quite different, innocent, structure: a haystack, a disused cottage, seaside kiosk, bus-stop shelter or railway signal box. It was not uncommon for pillboxes to be fitted with a dummy pitched roof to aid the deception. Some of these disguises bordered on the fanciful.
In some cases, the reinforced concrete roof was sculpted to make the distinctive form of a pillbox less obvious from the air.
In Somerset, along part of the Taunton stopline due to the shortage of material available, six pillboxes were coated with a mixture of cow manure and mud topped with straw as a form of natural concealment. Close to Axminster a square pillbox was disguised as a Romany caravan. During the summer months a scarecrow "family" and a horse made of straw were dressed and suitably arranged around the caravan to visually deceive that it was actually a manned pillbox.
Destruction, neglect, rediscovery and reuse
The great majority of Britain's static defences have been destroyed, a process that started even before the end of the war. Ditches and trenches have been filled; loopholes repaired; wood and metal re-cycled.
After the war, farmers, across whose land structures had been built were, in addition to receiving compensation, paid to fill in ditches and trenches and to demolish pillboxes. Today, hardly anything remains of the anti-tank ditches, but at the time they must have been the most conspicuous of all the fortifications; a few remain, much humbled, as field drains or field boundaries whereas others can be seen only as crop marks. In the case of pillboxes, the sum of £5 is sometimes mentioned to pay for demolition, but the challenge of demolishing such structures is considerable and it seems that most farmers pocketed the cash, treating it as compensation.
Today, it is very rare to find any part of Britain's defences other than that composed of concrete. Immediately after the war, there were more pressing matters to attend to than conserving the detritus of a battle that never happened. For decades, with the sole exception of Pevensey Castle — where the new fortifications were seen as a part of the building's history — there was never even a suggestion that anything should be deliberately conserved.
As the years passed, erosion and modern construction destroyed many structures: at the coast fortifications have tumbled into the sea or sunk into the sands on which they were built; yet other features have succumbed to road improvements or have been demolished to make way for other modern developments. For many of those that remain, neglect and the attentions of nature have achieved a degree of camouflage greater than that of during the Second War.
Years after the war, memories faded and in the public mind it became popular to assume that the few pillboxes and other concrete objects that could easily be seen were all that was done to defend Britain; that their purpose was just to bolster morale and that there would have been no realistic hope of resisting a German assault. Even the Home Guard came to be seen as something of a joke as exemplified by the BBC sitcom Dad's Army. Whereas, in fact, what can be seen today are just the most visible and robust remains of what was a massive programme of fortification that would likely have proven highly effective.
Extant war-time records were thought to be fairly poor, and nobody could be sure how many pillboxes and related hardened field defences had survived — or indeed, how many had been constructed in the first place. In the late 1970s, journalist Henry Wills began research on the topic eventually leading to publication of Pillboxes: A Study of UK Defences in 1985. Interest was stimulated, both public and professional; local surveys were carried out. Surveys culminated in the Defence of Britain Project which took place from 1995 to 2002 attempting to record all known military defence sites. From this and other surveys, it is estimated that some 28,000 pillboxes and other hardened field fortifications were constructed in the United Kingdom of which about 6,500 still survive. The project also resulted in the discovery of many relevant records.
For many pillboxes, a new use has been found. The type 28s, being internally spacious and having a large rear entrance are probably the most amenable to reuse and on farms and in gardens they serve as cattle sheds and storage lockers. Other, more imaginative pillbox applications recorded include use as a pub cellar, a conversion to a ladies toilet and an open-air theatre box office.
Some pillboxes have been converted to make roosts for bats. Pillboxes that are well dug-in and thick walled are naturally damp and provide a stable thermal environment that is required by bats that would otherwise hibernate in caves. With a few minor modifications, suitable pillboxes can be converted to artificial caves for bats.
- Dymchurch Redoubt
- Eastbourne Redoubt Home of the Combined Services Collection
- British anti-invasion preparations of World War II
- ^ John Hellis. "Why Pillbox?". Pillbox Study Group. http://www.pillbox-study-group.org.uk/whypillbox.htm. Retrieved 10 September 2009.
- ^ Some commentators make reference to the Ordnance QF 6 pounder rather than the older Hotchkiss 6 pdr, but this is in error.
- ^ Ruddy, 2003, p12.
- ^ "Photograph of extant Turnbull mount". http://www.users.globalnet.co.uk/~rwbarnes/defence/norwest/kirkbri_/kirkb-e-.htm. Retrieved 8 July 2006.
- ^ Alanbrooke, War Diaries, Entry 22 March 1940.
- ^ "Imperial War Museum Online Collection". Photograph number H 5110, Pillbox interior (appears to be a Type 28 with a 6 lb gun) with a few creature comforts. http://www.iwmcollections.org.uk/qryPhotoImg.asp. Retrieved 29 May 2006.
- ^ Ruddy, 2003, p9.
- ^ "Image of damaged pillbox revealing use of scrap metal". Robert Mallory's Bunkers Page. http://members.lycos.co.uk/Robertm/pillboxe3.htm. Retrieved 16 July 2006.
- ^ Wills, 1985, p56.
- ^ "Heatons Bridge pillbox". Wikimedia Commons. http://commons.wikimedia.org/wiki/File:Heatons_Bridge_pillbox.JPG. Retrieved 6 October 2010 - a pillbox of ad hoc design, having two stories in this case.
- ^ The numbers of each pillbox type cannot be known exactly because the Defence of Britain database is imperfect—admitting omissions, duplicates, misidentifications etc. Some commentators give the Type 22 as the most common, but the database gives the Type 24 as the most common. See Foot, 2006, p17.
- ^ Ruddy, 2003, p13, Type 22 (FW3/22).
- ^ "Type 22 pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/type_22_pillbox.html. Retrieved 9 July 2006.
- ^ "Type 22 pillbox.". Pillbox study group. http://www.pillbox-study-group.org.uk/type22page.htm. Retrieved 9 July 2006.
- ^ a b c d e f g h i "A Review Of The Defence Of Britain Project.". pp. section 6.4. http://www.britarch.ac.uk/projects/dob/review/index.html. Retrieved 22 March 2007.
- ^ Ruddy, 2003, p14, Type 23 (FW3/23).
- ^ "Type 23 pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/type_23_pillbox.html. Retrieved 9 July 2006.
- ^ "Type 23 pillbox.". Pillbox study group. http://www.pillbox-study-group.org.uk/type23page.htm. Retrieved 9 July 2006.
- ^ Ruddy, 2003, pp14-15, Type 24 (FW3/24).
- ^ "Type 24 pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/type_24_pillbox.html. Retrieved 9 July 2006.
- ^ "Type 24 pillbox.". Pillbox study group. http://www.pillbox-study-group.org.uk/type24page.htm. Retrieved 9 July 2006.
- ^ Ruddy, 2003, p15, Thick Walled Type 24.
- ^ The National Archives file WO 166/3443
- ^ Ruddy, 2003, p15, Type 25 (FW3/25).
- ^ "Type 25 pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/type_25_pillbox.html. Retrieved 9 July 2006.
- ^ "Type 25 pillbox.". Pillbox study group. http://www.pillbox-study-group.org.uk/type25page.htm. Retrieved 9 July 2006.
- ^ Ruddy, 2003, p16, Type 26 (FW3/26).
- ^ "Type 26 pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/type_26_pillbox.html. Retrieved 9 July 2006.
- ^ "Type 26 pillbox.". Pillbox study group. http://www.pillbox-study-group.org.uk/type26page.htm. Retrieved 9 July 2006.
- ^ Ruddy, 2003, p17, The Pre-fabricated Pillbox.
- ^ "Prefabricated pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/prefabricated_pillbox.html. Retrieved 10 July 2006.
- ^ Ward, William. "`prefab` pillbox.". Pillbox study group. http://www.pillbox-study-group.org.uk/prefabpillbox.htm. Retrieved 10 July 2006.
- ^ Ruddy, 2003, p17, Type 27 (FW3/27).
- ^ "Type 27 pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/type_27_pillbox.html. Retrieved 9 July 2006.
- ^ "Type 27 pillbox.". Pillbox study group. http://www.pillbox-study-group.org.uk/type27page.htm. Retrieved 9 July 2006.
- ^ Ruddy, 2003, pp18-19, Type 28 (FW3/22), Type 28A and Type 28A Twin.
- ^ "Type 28 pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/type_28_pillbox.html. Retrieved 9 July 2006.
- ^ "Type 28 pillbox.". Pillbox study group. http://www.pillbox-study-group.org.uk/type28page.htm. Retrieved 9 July 2006.
- ^ Ruddy, 2003, p16, Vickers Heavy Machine Gun Emplacement. NB other sources indicate 'medium machine gun emplacement'.
- ^ "Vickers MG Emplacement.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/vickers_mg_pillbox.html. Retrieved 9 July 2006.
- ^ "Vickers Medium Machine Gun (MMG) Emplacement". Pillbox study group. http://www.pillbox-study-group.org.uk/vickersmmgpage.htm. Retrieved 9 July 2006.
- ^ Mushroom Pillbox, Pillbox Study Group
- ^ Ruddy, 2003, p22, Regional Variations: Lozenge.
- ^ "Lozenge pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/lozenge_pillbox.html. Retrieved 9 July 2006.
- ^ Ruddy, 2003, p22, Regional Variations: Earred.
- ^ "Earred pillbox.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/earred_pillbox.html. Retrieved 9 July 2006.
- ^ Ruddy, J Austin. "Auburn Sands, Coastal Crust Defences, Bridlington". Pillbox study group. http://www.pillbox-study-group.org.uk/auburnsands.htm. Retrieved 9 July 2006.
- ^ Foot, 2006, pp163-164 pp168-169.
- ^ Ruddy, 2003, p14, Twin Type 23.
- ^ Ruddy, 2003, p22, Regional Variations: Dover Quad.
- ^ "Images of extant section post.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/section_post.html. Retrieved 3 July 2006.
- ^ Ruddy, 2003, p15.
- ^ Osborne, 2004, p259.
- ^ "Photographs of a Norcon pillbox by Martin Briscoe.". Archived from the original on 2007-01-01. http://web.archive.org/web/20070101173303/http://www.users.zetnet.co.uk/mbriscoe/PAGES/Beauly_Pillbox_2.htm. Retrieved 10 May 2006.
- ^ "Norcon pillbox.". Pillbox study group. http://www.pillbox-study-group.org.uk/norconpage.htm. Retrieved 6 July 2006.
- ^ Foot 2006, pp. 154–155.
- ^ "Ruck Machine Gun Post". Thesaurus. English Heritage. http://thesaurus.english-heritage.org.uk/thesaurus_term.asp?thes_no=365&term_no=123548. Retrieved 19 August 2010.
- ^ Machine gun posts constructed from hollow concrete blocks - HO 197/8, The National Archives
- ^ Foot 2006, p. 164.
- ^ Foot 2006, pp. 150 and 152.
- ^ Ruddy, 2003, p21, Pickett_Hamilton Fort.
- ^ "Pickett-Hamilton Fort.". http://www.users.globalnet.co.uk/~rwbarnes/defence/silloth_/phfort-.htm. Retrieved 11 June 2006.
- ^ "Picket-Hamilton fort.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/pickett_hamilton_pillbox.html. Retrieved 14 March 2007.
- ^ a b c d e f The Allan Williams Steel Revolving Turret 1940.
- ^ Ruddy, 2003, p23, Allan Williams Turret.
- ^ "Images of extant Allan Williams Turret with its pit.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/allan_williams_turret_4.html. Retrieved 28 June 2006.
- ^ "Rustproof Metal Window Co., Ltd. vs Inland Revenue Commissioners". 1947. http://www.indiankanoon.org/doc/210537/. Retrieved 19 May 2011.
- ^ "Allan Williams Turret". Pillbox study group. http://www.pillbox-study-group.org.uk/allanwilliamspage.htm. Retrieved 15 July 2006.
- ^ Behind the war memorial, Builth Wells
- ^ a b Wills 1985, pp. 21–22.
- ^ "Images of extant Tett Turret.". Pillboxes UK. http://s134542708.websitehome.co.uk/pillboxes/html/tett_turret_0.html. Retrieved 4 September 2010.
- ^ "Brookmans Park Newsletter (example of a spigot mortar emplacement at Brookmans Park).". http://www.brookmans.com/news/may03/spigotmortar.shtml. Retrieved 10 May 2006.
- ^ Ruddy, 2003, p23, Loopholed Walls.
- ^ Camouflage, 2007, Chapter III.
- ^ Foot, 2006, p626.
- ^ Ruddy, 2003, p11.
- ^ Roger Cox. "Surrealist who tried to paint a whole nation green". The Scotsman. http://living.scotsman.com/ViewArticle.aspx?articleid=2740837. Retrieved 4 March 2007.
- ^ Newark, 2007.
- ^ "Defence of Britain Project". Pillbox Camouflage. http://www.britarch.ac.uk/projects/dob/record2.html. Retrieved 19 February 2007.
- ^ Chris Alder. "Somerset County Gazette". Pillbox gets a makeover. http://www.somersetcountygazette.co.uk/search/display.var.1061487.0.pillbox_gets_a_makeover.php. Retrieved 27 January 2007.
- ^ "Imperial War Museum Online Collection". Photograph numbers H 3306 and H 3307, Pillbox disguised as a garage/parked car. http://www.iwmcollections.org.uk/qryPhotoImg.asp. Retrieved 29 May 2006.
- ^ Foot, 2006, p3.
- ^ Foot, 2006, p4, p516.
- ^ Image of anti-tank cubes subsumed by sand.
- ^ a b William Foot. "Defence of Britain Project". Pillboxes in the modern landscape. http://www.britarch.ac.uk/projects/dob/dl12d.html. Retrieved 19 February 2007.
- ^ Foot, 2006, p5.
- ^ Wills, 1985.
- ^ Denison, 2002.
- ^ "Defence of Britain Project". http://www.britarch.ac.uk/projects/dob/index.html. Retrieved 30 May 2006.
- ^ "A Review Of The Defence of Britain Project". Report. http://www.britarch.ac.uk/projects/dob/review/index.html. Retrieved 30 May 2006.
- ^ "Protecting and managing underground sites for bats (pdf), see section 6.4.". http://www.eurobats.org/documents/pdf/AC9/Doc_AC9_15_Protecting_underground_sites.pdf. Retrieved 18 May 2006.
- ^ "Pillbox converted to bat retreat". BBC News. 4 June 2006. http://news.bbc.co.uk/1/hi/england/4885642.stm. Retrieved 18 May 2006.
- anonymous (c1940). The Allan Williams Steel Revolving Turret.
- Alanbrooke, Field Marshal Lord (2001). War Diaries 1939-1945. Phoenix Press. ISBN 1-84212-526-5.
- Banks, Sir Donald (1946). Flame Over Britain. Sampson Low, Marston and Co.
- Cameron, A Bryce (2000). Under Sand, Ice & Sea. Trafford Publishing. ISBN 1-55212-319-7.
- Cox, Richard (1975). Operation Sea Lion. Thornton Cox. ISBN 0-902726-17-X.
- Cruickshank, Dan (2001). Invasion — Defending Britain from Attack. Boxtree. ISBN 0-7522-2029-2.
- Denison, Simon (June 2002). "Fortress Britain". British Archeology (65). http://www.britarch.ac.uk/BA/ba65/feat1.shtml. Retrieved 10 March 2007.
- Evans, Martin Marix (2004). Invasion! Operation Sealion 1940. Longman. ISBN 0-582-77294-X.
- Foot, William (2006). Beaches, fields, streets, and hills ... the anti-invasion landscapes of England, 1940. Council for British Archaeology. ISBN 1-902771-53-2.
- Hayward, James (2001). The Bodies On The Beach — Sealion, Shingle Street and the Burning Sea Myth of 1940. CD41 Publishing. ISBN 0-9540549-0-3.
- Lowry, Bernard (2004). British Home Defences 1940–45. Osprey Publishing. ISBN 1-84176-767-0.
- Newark, Tim (March 2007). "Now you see it... Now You Don't.". History Today.
- Osborne, Mike (2004). Defending Britain ... twentieth century military structures in the landscape. Tempus Publishing. ISBN 0-7524-3134-X.
- Osborne, Mike (2008). Pillboxes of Britain and Ireland. Tempus Publishing. ISBN 978-0-7524-4329-4.
- Pollard, Tony; Oliver, Neil (2003). Two Men in a Trench II: Uncovering the Secrets of British Battlefields. Michael Joseph. ISBN 978-0718145941.
- Ruddy, Austin (2003). British Anti-Invasion Defences 1940–1945. Historic Military Press. ISBN 1-901313-20-4.
- White, John Baker (1955). The Big Lie. Evans Brothers.
- Wills, Henry (1985). Pillboxes: A Study of UK Defences. Leo Cooper. ISBN 0-436-57360-1.
- WW2 People's War is an online archive of wartime memories contributed by members of the public and gathered by the BBC. The archive can be found at http://www.bbc.co.uk/ww2peopleswar/.
- Camouflage: Military Training Pamphlet No. 46. Part 2: Field Defences (July 1941) The War Office.
- C Bird -Silent Sentinels - A study of the fixed defences constructed in Norfolk during WWI and WWII (1999) ISBN 0-948400-81-1
- Tim Denton Wartime Defences on the Basingstoke Canal Pillbox Study Group, 2009
- William Foot - The Battlefields That Nearly Were. Defended England 1940 (Stroud: Tempus Publishing 2006) ISBN 978-0-7524-3849-8
- Mike Osborne - Defending Britain ... twentieth century military structures in the landscape (2004) ISBN 0-7524-3134-X
- Mike Osborne - 20th Century Defences in Britain (2003) ISBN 0-9540378-1-2
- Mike Osborne - Pillboxes of Britain and Ireland (2008) ISBN 978-0-7524-4329-4
- Stewart Ross - World War II Britain. History from Buildings (London:Franklin Watts 2006) ISBN 0-7496-6468-1
- The German Threat to Britain in World War Two. By Dan Cruickshank. BBC website.
- The Real Dad's Army[dead link] - TV Documentary.
- Pillboxes for bats.
- Pillboxes on BBC Inside Out website.
- English Heritage: Understanding & Recording Military Sites.
- Churchill's mysterious map.
- Building Pillboxes: A Personal Story by E. S. Hardie. Pillbox Study Group
- The Real Dad's Army. Channel 4 documentary.
- Attack On A Pillbox - news item featuring a British training exercise. (Newsreel). British Pathé. 10 February 1941. http://www.britishpathe.com/record.php?id=12050. Retrieved 6 March 2010.
- Defence of Britain database.
- Pillbox study group.
- Pillbox Study Group A 300 member group dedicated to the study and preservation of 20th Century Anti-Invasion Defences. The groups 200 page website details many specific defences in great detail and specific sites are listed by the members throughout Britain and the world. Membership is open to all interested in these defences. Please visit the site for more details.
- Pillboxes UK Details of many specify sites throughout Britain.
- Caithness: WW2 Defences in Caithness By Andrew Guttridge.
- Cumbria: Defence of Cumbria in the 20th Century.
- Cumbria: Defence of the port of Workington.
- Devon: Eastern Devon around Seaton and Axmouth.
- Dorset: Isle of Purbeck, Abbotsbury.
- East Sussex: http://www.pillbox.org.uk/ The Defence of East Sussex Project
- Hampshire: Defences at Breamore Mill, Downton, Hampshire. Pillbox Study Group
- Hampshire: Defending Chequers Bridge, Crookham Village, Hampshire by Colin Alexander. Pillbox Study Group
- Hertfordshire: Fortress Hertfordshire.
- Kent: Dover and Western Heights[dead link].
- South London: C4 Time Team at Shooters Hill.
- Leeds-Liverpool canal: Western Command Stop Line #14
- Norfolk: WW2 Coastal Defences Salthouse, Kelling & Weybourne North Norfolk
- Norfolk: 20th Century Defensive Structures...
- Northumberland: 20th Century Defensive Structures...
- Orkney: 20th Century Defensive Structures...
- Somerset: Somerset pillboxes.
- Surrey: Pillboxes in Surrey.
- Sussex: Newhaven[dead link].
- Sussex: Redoubt Fortress Museum Home of the Combined Service Museum
- West Sussex: 1940 in Findon Stories and photographs of a fortified village on Britain's southern coast.
- Yorkshire: The Defences of a Coastal Inlet, Sand-le-Mere, East Yorkshire by Austin J Ruddy. Pillbox Study Group
- Lincolnshire: World War 2 Military Relics Trail around Skegness, Lincolnshire.
Centre of Great Britain
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