Spigot Mortar Emplacement, Farnham Park

Summary

An emplacement for the Blacker Bombard or 29mm spigot mortar, built 1941-1942. This example is representative of Directorate of Fortifications and Works drawing 55280 and survives intact. The emplacement consists of a central concrete thimble, with four brick built, concrete topped ammunition lockers built into the surrounding walls of an octagonal pit. Only the top of these structures are visible, although they are understood to survive intact beneath backfill.

Reasons for Designation

The spigot mortar emplacement in the south-west corner of Farnham Park, Surrey, is scheduled for the following principal reasons:

* Survival: it is understood that the structure is well preserved, with all four ammunition lockers, as well as the pedestal, remaining intact;

* Rarity: this spigot mortar position is a rare example of a fully intact emplacement;

* Period: spigot mortar emplacements were an important component of the nation’s Second World War defence policy and are therefore highly representative of this period;

* Potential: the site has the potential to enhance our understanding of the construction, function and use of this type of defensive structure;

* Group value: with several designated assets, including the Farnham Park registered landscape within which this emplacement stands (NHLE 1001499, Grade II), The Park Ranger’s House (NHLE 1378305, Grade II*) which became the headquarters for the local air raid wardens and Farnham Castle (NHLE 1044677 and 1012181, Grade I and Scheduled Ancient Monument) which housed the Camouflage Development and Training Centre from 1940.

History

Following the evacuation of the British Expeditionary Force from Dunkirk in 1940, Britain’s defences were strengthened against the very real threat of a German invasion. Diverse types of defensive structures were built in large numbers across the whole country, some of the most common including road and rail blocks, earthwork gun emplacements, barbed wire entanglements, anti-tank defences and pillboxes. These defensive structures were generally grouped, either at vulnerable or strategically important nodal points, around vital installations such as airfields, or arranged in linear defensive systems called stop lines, which were intended to obstruct the enemy advance. One particular weakness identified in Britain’s defences was a grave shortage of anti-tank guns; 840 had been left behind in France following the Dunkirk evacuation and only 167 were available in Britain. Besides a lack of weaponry, the required ammunition was in such short supply that regulations prohibited the firing of even a single round for training purposes. One possible solution to this deficit was an infantry anti-tank weapon designed by Stuart Blacker, a Lieutenant Colonel in the Territorial Army. Known as the ‘Blacker Bombard’ this was a based on his earlier version of a spigot mortar. Unlike conventional mortars with a barrel, a spigot mortar has a steel ‘spigot’ onto which the projectile slides. When the mortar is fired, the spigot explodes the propellant charge housed in the tail of the projectile and fires the round. Blacker’s idea was to swivel-mount a spigot mortar with a trigger firing mechanism for ease of transportation and operation, and to use it in an anti-tank role. It was also fitted with a portable mounting consisting of four folding legs.

The design for the Blacker Bombard dates back to 1939, although it was not accepted by the War Office until after the events of Dunkirk. The plan was submitted to the head of the Military Intelligence Research department, Major Millis Jefferis, who was receptive to the idea, although other government officials initially opposed. Prime Minister Winston Churchill attended a demonstration of the weapon on 18 August 1940, and on his orders the weapon was put into full production. By mid-December about 8000 of an initial order of 16,000 had been issued, and the initial order was increased to 28,000. Eventually nearly 29,000 were made. On 14 September 1941, the Directorate of Fortifications and Works (DFW) published drawing number 55280. This was an important development which introduced the designs for a pedestal mounting for the weapon, replacing the heavy folding legs with a fixed emplacement. By using these pre-prepared emplacements, the weapon could benefit from enhanced portability and stability, whilst still offering sufficient accuracy and protection for the crew. The plan form is discussed to a fuller extent in the Details section of this report.

Farnham saw significant activity during the Second World War. The town, although not designated as a nodal point, was seen as a vital centre of communications and thus was very well defended. Farnham also had an integral position in the General Headquarters (GHQ) Anti-Tank Line. GHQ Line A ran south from Reading to Farnham, while Line B ran east from Farnham through Godalming. Farnham Castle was a designated strong point along this line of defence, and as a consequence there are a substantial number of sites in the surrounding area recorded on the National Record of the Historic Environment. This includes numerous anti-invasion defences such as pill boxes and anti-glider posts, as well as an air raid shelter. Furthermore, The Park Ranger’s House (National Heritage List for England reference 1378305, listed at Grade II*) became the headquarters for the local air raid wardens and The War Office set up the Camouflage Development and Training Centre at Farnham Castle (NHLE reference 1044677, listed at Grade I) in 1940.

The exact nature of the emplacement at Farnham Park is unclear. The positioning of the site at the bottom of a slope, would potentially limit the effectiveness of the weapon, and based on the DFW drawing, the most likely line of fire at this site is aiming toward the south. It has been suggested that during the Second World War, the eastern wall of Park Row, the footpath leading to Bear Lane, was demolished, thus opening up a narrow line of fire stretching down Bear Lane, as far as the junction with The Borough. This is based on the fact that the wall is constructed of a rat trap bond which was prevalent after the war, due to a shortage of bricks. This narrow line of fire would also have had a defensive benefit, complicating any attempts for an enemy to return fire. Given the integral part of Farnham in the course of GHQ Lines and the fact that Farnham Castle was a designated strong point, the most feasible suggestion is that this was an ambush position forming part of these defences. However, the possibility that this emplacement was used for training purposes cannot be completely ruled out.

Details

PRINCIPAL ELEMENTS
This is an emplacement for a 29mm spigot mortar, also known as the Blacker Bombard, dating from 1941-1942. This example would appear to have been built exactly according to the Directorate of Fortifications and Works plan. The type site would comprise a concrete thimble of approximately 1m diameter and 1m in height, with a central steel pin which would engage the underside of the weapon and form a swivel mounting. The thimble was to be centred in a pit about 1.2m deep giving access all around, with up to four concrete ammunition lockers recessed into the walls. A deeper approach trench was also included in the plan.

DESCRIPTION
The site was subject to an archaeological investigation in 1998 and was well documented in the excavation report. After the excavation the site was subsequently backfilled and remains largely buried. The top of the pedestal and steel pin, as well as the concrete tops of the ammunition lockers are all that are visible at present (2022). However, the rest of the structure is understood to survive intact below ground.

This example consists of a polygonal pit, which is 1.01m deep and 2.5m in diameter, finished with a concrete floor. The hole is partially lined with four brick walled and concrete topped ammunition lockers which are set 60cm back into the wall of the pit. In the centre of the pit is the large circular concrete thimble, roughly 1.17m diameter with a curved top capped with a circular iron plate in the centre. This holds the steel pin or pivot, which extends approximately 10cm. The top surface of two of the ammunition lockers also have contemporary graffiti which appears to have been drawn when the concrete was still wet. The westernmost locker has a swastika and a hammer-and-sickle while its neighbour to the south has a cross of St George surrounded by a G shape, along with a crude arrowhead.

EXTENT OF SCHEDULING
The scheduled monument includes the entire known extent of the emplacement.

Sources

Books and journals
Alexander, C, Ironside's Line: The definitive guide to the General Headquarters Line, (1998)
Dobinson, C S, Twentieth Century Fortifications in England Volume II Anti Invasion Defences of WWII, (1996), 185-6
Foot, W, Beaches, Fields, Streets and Hills: the anti-invasion landscape of England 1940, (2006), 18
Graham, D, Farnham Park landscape survey and archaeological excavations, (1998), 15-19

Websites
Defence of Britain survey database, accessed 11/01/2017 from http://archaeologydataservice.ac.uk/archives/view/dob/ai_q.cfm
Specialist Second World War equipment website, accessed 12/01/2017 from http://www.wwiiequipment.com/index.php?option=com_content&view=article&id=93:the-blacker-bombard&catid=47:british&Itemid=59

End of official list entry

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