Bofors gun emplacement and attached pillbox

Summary

40mm Bofors Light Anti-aircraft (LAA) gun emplacement with attached Type 23 pillbox.

Reasons for Designation

This 40mm Bofors Light Anti-aircraft gun emplacement and attached Type 23 pillbox,is listed at Grade II for the following principal reasons:* Architectural interest and degree of survival:the design of the gun emplacement and attached pillbox reflects its specific dual-role–low-level anti-aircraft and ground defence.It is built to a higher standard than most equivalent wartime structures;* Rarity:it is an extremely rare example of a permanent 40mm Bofors light anti-aircraft gun emplacement with attached pillbox; * Historic associations: the structure is directly associated with the Luftwaffe bombing raids of 1940 and 1941 against ROF Chorley;unusually, it was operated as a light anti-aircraft defence both by the regular army and the Home Guard,and it has a well documented history held at The National Archives,Kew.

History

The Royal Ordnance Factory - No.1 Chorley was the first of eight such‘filling factories’constructed between 1936 and 1940,to substantially increase the manufacture of munitions in anticipation of and during the Second World War.The sites had a wide geographical distribution,chiefly towards the northern and western sides of the United Kingdom,to ensure a degree of protection from aerial bombing.Once Germany had invaded Norway,Denmark,France and the Low Countries,this geographical advantage was lost,as all of the sites were then within the effective range of the Luftwaffe bombers;consequently,light anti-aircraft defences were provided and Chorley became Vulnerable Point(VP)426.Initially it was defended only by.303 Lewis light anti-aircraft machine guns,but as more powerful guns became available during 1941,the defences were improved by the addition of a number of 40mm Mk.I Bofors guns.These guns were usually considered as being‘mobile’by the army and were mounted on a towed wheeled gun carriage,which could be quickly brought to readiness by lowering the gun platform,extending the cruciform out-riggers,removing the wheels and then levelling up the mounting using screw jacks.However,when the guns were deployed on a more permanent basis to defend a particular site,like ROF Chorley,the gun and its mounting was dismounted from the platform and was fixed onto a concrete holdfast at the centre of a gun emplacement.This was the arrangement used for the 40mm Bofors gun that was sited on the hill to the north-east of ROF Chorley at Whittle-Le-Woods.As this gun was manned on an around the clock basis,the gun detachment was provided with a shelter,which could double as a pillbox had the enemy attempted to use airborne troops to attack the factory.The Bofors gun was finally stood down on 1st November 1944.

Details

40mm Bofors light anti-aircraft gun emplacement with predictor pit and a detachment shelter,based on a design by the Directorate of Fortifications and Works,built November–December 1940,to defend the Royal Ordnance Factory Chorley,(Vulnerable Point 426).MATERIALS:fair-faced brick walls with concrete gun platform,floors and roof.PLAN:circular-plan,semi-sunken gun emplacement with an attached semi-sunken detachment shelter in the form of a rectangular-plan Type 23 pillbox.EXTERIOR:the circular-plan pit of the emplacement is approximately 4.57m in diameter.The concrete gun floor is approximately 0.6m below ground-level and has a recessed gutter running around its circumference.The emplacement has a low brick retaining wall surrounding it,with four ready-use ammunition lockers set back into the low wall.Situated at the centre of the gun floor is a 1.52m diameter,0.76m high concrete holdfast pedestal.A square cable duct enters the pedestal on the south-western side and rises vertically within the centre of it.A square steel mounting frame with six projecting holdfast bolts is set in the upper surface of the pedestal.A circular brick-lined predictor pit with a cable duct in its floor is situated on the south-western side of the emplacement,and a semi-sunken rectangular-plan Type 23 pillbox is attached to the north-eastern side.The emplacement and the pillbox appear to have been built contemporaneously as one structure.The pillbox is built to a‘blast and splinter-proof’specification,with 0.58m thick walls and the covered chamber has a flat 0.3m thick reinforced concrete roof,and three of the walls are pierced by narrow splay rifle embrasures.The open forecourt to the rear functioned as a weapons pit for a pintle-mounted Lewis anti-aircraft light machine gun(AALMG)and was entered by a gap in the wall at its western corner.At some point in time,the walls of the weapons pit have been reduced in height and are flush with the surrounding ground-level.INTERIOR:the pillbox comprises of a single square-plan room with fair-faced brick walls and a concrete floor,with a central brick-built anti-ricochet wall.It is entered down steps from the weapons pit through a low doorway in the western corner of the pillbox.

Sources

Books and journals
Cocroft, W, Dangerous Energy The Archaeology of Gunpowder and Military Explosives Manufacture, (2000)
Annon, , Handbook for the Ordnance, Q.F. 40-mm., Mark I on Mountings, 40-mm., A.A., Marks I, IA, IB, II and III, (1941)
Terry J. Gander, , The 40mm Bofors Gun, (1986)

Other
Aaron Goode, Robin Taylor-Wilson, Guy Thompson, World War Two Defence Installation, Lucas Green, Whittle-le Woods, Chorley, Lancashire, March 2013,

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