Three Pickett-Hamilton forts at Swanton Morley airfield


Heritage Category: Scheduled Monument

List Entry Number: 1020780

Date first listed: 29-Jan-2003


Ordnance survey map of Three Pickett-Hamilton forts at Swanton Morley airfield
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The building or site itself may lie within the boundary of more than one authority.

County: Norfolk

District: Breckland (District Authority)

Parish: Hoe

National Grid Reference: TF 99952 18520, TG 00084 18736, TG 00541 18993


Legacy Record - This information may be included in the List Entry Details.

Reasons for Designation

The importance of defending airfields against attack was realised before the outbreak of World War II and a strategy evolved as the war went on. Initially based on the principle of defence against air attack, anti-aircraft guns, air raid shelters and dispersed layouts, with fighter or `blast' pens to protect dispersed aircraft, are characteristics of this early phase. With time, however, the capture of the airfield became a more significant threat, and it was in this phase that the majority of surviving defence structures were constructed, mostly in the form of pillboxes and other types of machine gun post. The scale of airfield defence depended on the likelihood of attack, with those airfields in south or east England, and those close to navigable rivers, ports and dockyards being more heavily defended. But the types of structure used were fairly standard. For defence against air attack there were anti-aircraft gun positions, either small machine gun posts or more substantial towers for Bofors guns; air raid shelters were common, with many examples on each airfield; and for aircraft, widely dispersed to reduce the potential effects of attack, fighter pens were provided. These were groups together, usually in threes, and took the form of `E' shaped earthworks with shelter for ground crew. Night fighter stations also had sleep shelters where the crew could rest. For defence against capture, pillboxes were provided. These fortified gun positions took many forms, from standard ministry designs used throughout Britain and in all contexts, to designs specifically for airfield defence. Three Pickett-Hamilton forts were issued to many airfields and located on the flying field itself. Normally level with the ground, these forts were occupied by two persons who entered through the roof before raising the structure by a pneumatic mechanism to bring fire on the invading force. Other types of gun position include the Seagull trench, a complex linear defensive position, and rounded `Mushroom' pillboxes, while fighter pens were often protected by defended walls. Finally, airfield defence was co-ordinated from a Battle Headquarters, a heavily built structure of which under and above ground examples are known. Defences survive on a number of airfields, though few in anything like the original form or configuration, or with their Battle Headquarters. Examples are considered to be of particular importance where the defence provision is near complete, or where a portion of the airfield represents the nature of airfield defence that existed more widely across the site. Surviving structures will often be given coherence and context by surviving lengths of perimeter track and the concrete dispersal pads. In addition, some types of defence structure are rare survivals nationally, and all examples of Pickett- Hamilton forts, fighter pens and their associated sleep shelters, gun positions and Battle Headquarters closely associated with defence structures, are of national importance.

The three Pickett-Hamilton forts at Swanton Morley airfield are of importance as comparatively rare examples of an unusual and innovative type of airfield defence installation. The outer structure and lifting heads of all three remain intact and they are known or believed to retain internal features, including parts of the hydraulic mechanism.


Legacy Record - This information may be included in the List Entry Details.


The monument, which is in three separate areas of protection, includes three Pickett-Hamilton forts which were installed in late 1940 as part of the ground defences on Swanton Morley airfield.

Swanton Morley airfield was designed as a medium bomber station with a grass strip flying field, and opened in September 1940 as a full station within No.2 Group of Bomber Command. In the first year of operation it was a base for squadrons flying Blenheims and was also used by Spitfires of 152 Squadron. It was also the airfield where the de Havilland Mosquito first entered service. In late 1941 it received No.226 Squadron, equipped first with Douglas Boston IIIs and then, from 1943, with Mitchells. In June 1942 it was the scene of the launch of the first combined British-American bombing raid, at which both Churchill and Eisenhower were present. Swanton Morley remained in use as an RAF station until 1995 and the grass flying field was used for glider training.

Pickett-Hamilton forts were designed specifically for airfield defence on the flying field and are a form of retractable pill box, the upper section of which could be lowered flush with the ground surface when not in use, so as not to obstruct aircraft landing or taking off. Each consisted of two hollow, concentric pre-cast concrete drums resting on a concrete base. The outer drum and base, measuring approximately 2.5m in depth were sunk into the ground. The inner drum, pierced by three rifle loopholes, formed the lifting head and was designed to be raised approximately 0.75m by means of a central jack, using a compressed air bottle or hand pump, although this system proved unreliable and was later supplemented by oil pumps. When the lifting head was in the lowered position an external flange rested on the upper section of the outer drum, which incorporated a pre-cast surround or collar. Access was by means of a metal hatch in the roof of the lifting head and metal rungs set into the inner face. The interior fittings included a free standing circular firing step around the central column, a small electric light, and a telephone for communication with the airfield battle headquarters.

The concrete tops of the lifting heads of the three Pickett-Hamilton forts at Swanton Morley are partly overgrown but visible, with the metal hatches set off centre. If fully exposed they would be around 2m in diameter, with the upper sections of the outer drums extending about 0.3m beyond, giving an overall diameter of 2.6m. They are located on the flying field to the north west of the line of the main runway, which is visible on aerial photographs taken by the RAF in 1946 and is still marked by concrete pads for lights. It was aligned north east-south west, with subsidiary runways running north west-south east and WNW-ESE. The southernmost of the three forts is located approximately 720m WSW of a triangulation pillar and 80m from the line of the runway. The access hatch is secured by a bar across it, but the lifting mechanism is recorded as intact, though rusted. The second lies some 250m to the NNE of this, about 140m from the line of the main runway and within the triangle which this formed with the two subsidiary runways. The interior is completely flooded but is thought to contain original features. The third is located in the north eastern part of the flying field, about 254m north east of the second and 20m from the line of the main runway. This has been partly infilled, but the top of the column of the jack remains visible.

The bar which has been installed to secure the hatch of the first Pickett-Hamilton fort is excluded from the scheduling although the hatch itself is included.

MAP EXTRACT The site of the monument is shown on the attached map extract. It includes a 1 metre boundary around the archaeological features, considered to be essential for the monument's support and preservation.


The contents of this record have been generated from a legacy data system.

Legacy System number: 30607

Legacy System: RSM


Books and journals
Dobinson, C S, Twentieth Century Fortifications in England, (2000), 58,60
Dobinson, C S, Twentieth Century Fortifications in England, (2000), 58,60
Dobinson, C S, Twentieth Century Fortifications in England, (2000), 58, 60
Norfolk: 2830, (1994)

End of official listing