All pillboxes are concrete, but some are more concrete than others

Location: Allhallows, Kent (eDOB e04961)

In this first example, I have a Type 24 concrete bulletproof pillbox. It has been cast in situ, using wooden planks as shuttering both inside and out. A three-dimensional mould would have been made from the planks, supported externally by a scaffold of steel or wood, and both internal and external wooden shutters would have been tied together using wire to also stop them from splaying under the weight of the wet concrete. This type of formwork leaves characteristic seams in the concrete where the boards are joined. Where the concrete is very fine, you can even make out the wood grain.

Location: Cuckmere Haven, East Sussex (eDOB e06063)

This distinctive pillbox is a Type 25 Armco variant. So-called because of the American company Armco who manufactured the steel corrugated sheets that formed the form for the casting of these boxes. Some examples still retain their steel sheeting, but I have no evidence to suggest this was part of the original design or if it had not been removed for some other reason.

Location: Buchannan Battery, Orkney (eDOB e07127)

Strictly not a pillbox but I had to include this example of formwork. I can identify three different materials used in the casting of this Battery Observation Post; the distinctive corrugated iron section to the side, but there are also signs of wooden planks being used to form the upper section of the structure, and the bottom section of the rear appears to have been cast using wooden sheets as the formwork. It appears to also have been cast in three distinct phases judging by the visible layers in the concrete; the earlier layers have been allowed to set fully before the pour continued resulting in a non-homogenous wall structure. This is most likely a symptom of the difficulties in sourcing raw materials at the time.

Location: Shanes Park, County Antrim (eDOB e24511)

The red-brick pillbox is probably the one that people first think of when they think of these second world war defences. Rather far from being constructed entirely from red brick, this readily available material is used as a form of shuttering with a core of concrete.

In this example of a Type 24, large precast concrete lintels have been used above the loopholes and door to the rear. Interestingly, the floor of this pillbox has been laid in red brick and not the characteristic concrete as is often seen.

Location: River Medway, Kent (eDOB e05683)

A sorry looking example, this once brick-clad pillbox has been stripped of its bricks leaving the concrete core. The impressions of the bricks can still be seen on the exposed concrete face.

Location: Winchcombe, Gloucestershire (eDOB e11504)

This Type 24 pillbox has been constructed using the best materials for the job and was not rushed. This early was example constructed in August 1940¹The construction crew left the date of construction written in concrete on the inside. and utilised wooden shuttering on the inside, corrugated iron for the roof, and has a brick anti-ricochet wall on the inside. The outside, however, has been built using local stone laid with concrete. It is likely this external wall was laid first, then the internal shuttering constructed, and the concrete poured. The loopholes would have been cast using their own formwork at the same time as the main pour.

Location: Belfast, County Down (eDOB e24377)

It is the interior roof in this image that I want to draw your attention to. Sheets of corrugated iron have been used as a form when it came to casting the roof, and they have been left in-situ. Slowly rusting and deteriorating in the damp Northern Irish climate.

I have not seen corrugated iron used very often for casting the roof of pillboxes, but the same technique was also employed in the anti-tank gunnery range buildings near the Giants Causeway. Perhaps the same contractors of Royal Engineers constructed both sites.

Location: Arlingham, Gloucestershire (eDOB e02988)

A variant of a Type 26 pillbox, there are four to the west of Arlingham in Gloucestershire that appear to have been constructed using a combination of precast concrete panels and conventional wooden shuttering. The panels, used on the external walls, internal walls and the interior roof are similar in design to the wall sections of prefabricated garages; but their use in this instance is as shuttering for a central core of concrete.

They are very similar in construction to an example in Aylesford, Kent (eDOB e02992).

Location: Newtownards, County Down (eDOB e24506)

The shuttering inside and out on this pillbox is precast concrete panels that appear to be paving slabs. The concrete seams around the top and edges of the pillbox suggest traditional shuttering was also used, or even to a limited extent to encase the slabs during the pour. They would have been difficult to hold in place if the walls were cast in one pour, so perhaps the concrete was poured level-by-level as there is no evidence of any tying being used to secure the slabs to the structure.

The pillbox (eDOB e24754) on the hill between Donaghadee and Millisle has also been constructed using this method.

Location: Buchannan Battery, Flotta (eDOB e07127)

Not technically a pillbox, but I had to include a second example from Buchanan Battery on Flotta. On a much larger scale than the pillboxes above, this three-level battery observation post has been cast using large precast concrete panels laid horizontally as shuttering.

Location: Lywara, Hoy (eDOB e03030)

Arguably the only real precast concrete pillbox of the war; the Norcon provided light protection from small arms to the occupants. Supplementary protection would have been provided from sandbags or earth banks against the sides.

It is not to be confused with the 1980 Yarnold Sangar which can still be seen around the perimeter of many Cold War airforce sites.

Location: Lympne, Kent (eDOB 28928)

A retractable concrete turret designed for airfield defence, the Pickett-Hamilton fort was constructed from two precast concrete pipes; one sitting inside a larger, set into the ground. The top of the pillbox was flush with the ground until manually raised using a hydraulic jack by the crew inside. In this example, the steel reinforcing framework can be seen. The roof of the pillbox would have also protruded around the circumference but has since been damaged. Entry and exit of the pillbox were through a roof hatch, and internal space to work and operate weapons was very limited.

Location: Pett Level, East Sussex (eDOB e03952)

I found this pillbox by chance while on a hike along the coast a few years ago. On first inspection, it appears to be a standard Type 24 constructed with concrete block, similar to breeze blocks. Upon closer inspection, the blocks appear to be have been precast, including what must be bespoke corner blocks angled specifically for this design of pillbox. The aggregate in the concrete appears to be beach gravel which may have been collected locally from the nearby beach.

A lime mortar has been used to bond the block together which has eroded out of the top few courses of brick, and the calcium can be seen staining the outside of the pillbox.

If these blocks are indeed precast it has a lot of similarities to the Christchurch Block Sangar developed in the mid-1980s.

Location: Pirbright, Surrey (eDOB e23440)

A truly prefabricated kit pillbox, manufactured by the Stent Company, this pillbox could be erected on site relatively quickly using slotted upright beams and precast concrete panels bolted together and then filled with concrete. Precast loopholes were also supplied that extended between the inner and outer walls.

Location: Winchcombe, Gloucestershire (eDOB e28027)

Possibly one of a kind, this sandbag pillbox is similar to a circular Type 25, but has been made with concrete-filled hessian sacks that would have laid dry, and as the concrete was wetted it would have set.

This variant is very similar to Beehive-type pillboxes found around Northumberland but appears to be smaller.