Exploring Kent's Past

It should not be assumed that this site is publicly accessible and it may be on private property. Do not trespass.

Monument details

Summary

Building Q14, Fort Halstead, former purpose-built assembly building for the atomic bomb prototype warhead, late 1940s.

Monument Types

• WORKSHOP (Modern - 1947 AD to 2050 AD)

Full description

If you do not understand anything on this page please contact us.

Building Q14, Fort Halstead, former purpose-built assembly building for the atomic bomb prototype warhead, late 1940s. Late C20-early C21 modifications.

MATERIALS: Red brick in Stretcher bond encasing presumed steel-frame. Concrete roof.

PLAN: Rectangular two-storey, flat-roofed building oriented N-S. Ground floor double-height workshop. First floor reached by staircase at S end.

EXTERIOR: Double-height ground floor. Main entrance in S elevation through glazed double doors. Further pedestrian entrances to its E (now blocked) and at NE corner of building. Blocked large equipment entrance to SW retaining its original exterior wall light. Door head suggestive of former roller shutter door, now partly obscured by later plant room (the latter is not of special interest.) E elevation, which was public facing at the edge of the HER compound until 1952 when the boundary moved out to the E, originally blind at ground floor level, presumably to conceal the highly secretive nature of the work taking place inside. Current ground floor windows therefore secondary insertions. Form of original fenestration to W and N elevations remains legible as double-height windows to the ground floor to light the workshop inside. These large openings now bricked up with smaller ground floor windows inserted. All first floor windows are UPVC replacements although re-use original window openings. Fire escape to N elevation. (Replacement uPVC windows and the fire escape are not of special interest.)

On the w elevation a memorial plaque bearing the crest of the Royal Armament Research and Development Establishment reads: 'ln this building a group of scientists & engineers led by the then Dr W G Penney worked on United Kingdom atomic warheads during the period 1946 to 1952. This plaque was unveiled on 6th April 1982 by Lord Penney OM. KBE. MA. PhD. D Sc. FRS.'

INTERIOR:
Not inspected but ground floor viewed through windows. With the exception of the S entrance area and staircase, the ground floor comprises a single double-height workshop space which has a later inserted ceiling. An English Heritage internal inspection in May 2008 confirmed steel framing in the ceiling void of the workshop area although it was not possible to establish whether this was structural or a gantry for the travelling crane which is known to have been here originally. Staircase appears slighily modified with replacement modern treads. The Waterman gazetteer (2009)
confirms that the first floor has a spine corridor providing access to office space.

HISTORY:
Fort Halstead is a late C19 mobilisation centre, one of a ring of thirteen similar sites interspersed with entrenchments which were constructed to protect London in the 1890s against any potential invading force. These mobilisation centres were intended to be nodal points where a volunteer force could collect equipment and ammunition and defend the capital in the event of invasion. The capital was not encircled by these centres but was protected to its north-east, east and south, the anticipated directions of attack, and their construction represents a lack of confidence in the Royal Navy's ability to protect the country from its enemies at that time. Plans for Fort Halstead were drawn up by 1894 and it was probably constructed between 1895 and 1897. During the First World War the fort continued to be used as a defendable ammunition store, forming part of a London stopline (an anti-invasion defensive line) with a laboratory (possibly for the inspection of ammunition) built there in 1914 (building F14). ln 1921 it was sold to a private individual.

ln 1937 Fort Halstead was repurchased by the war office in order to provide accommodation for the Projectile Development Establishment (established here in 1938 under the directorship of Alwyn Crow) as it provided a remote and contained site for rocket development. lnterest in rocketry had revived in 1936 with initial work taking place in the Ballistics Branch at the Royal Arsenal in woolwich under Dr H J poole. However, woolwich was soon considered an inappropriate location given safety concerns, not least the proximity of dense populations: Fort Halstead was preferable in this respect. one experimental filling shed (building F11), is the earliest surviving building in England to be associated with rocketry. lt is from the late 1930s that the Fort Halstead site began to expand with a number of buildings constructed both inside and outside of the fort, including some of those under assessment here. ln 1940 the Armament Research and Armament Design departments took up residence at Halstead Place nearby.

At the end of the war, research continued although in a scaled-down form, but in January 1947 the British cabinet took the decision to proceed with the development of an atomic bomb. ln May of the same year this task was
entrusted to William Penney, Chief Superintendent of Armaments Research (CSAR) at Fort Halstead. Penney was a physicist and had been a leading member of the wartime British Mission to the United States Manhattan Project which had been responsible for creating the first atomic bombs. He played a prominent role in the project, and in addition to his scientific contributions also sat on the Target Committee, which discussed which Japanese cities should be attacked, and flew with the mission that dropped the bomb on Nagasaki to film its results. Fort Halstead thus
became the headquarters of High Explosives Research (HER), a top secret research branch whose name also hid the true focus of its work which was to develop Britain's first atomic bomb. Many purpose-built structures were erected both inside and outside the fort including electronics, engineering, mathematics and theoretical physic departments provided with drawing offices, laboratories and test stands, all within a secure fenced enclave. By the end of 1950, the atomic bomb project (developing the Mark 1 warhead which when assembled in its casing for service was known as 'Blue Danube') dominated work at Fort Halstead with nearly two thirds of the c1000 posts allocated to HER. The link between this project and the fort was a closely guarded secret. Even within government all orders were routed through the largely civil Atomic Energy Research Establishment (AERE) Hanruell, Oxfordshire, until 1949.

ln common with other government research establishments involved with weaponry research and development there is very little in the public domain in the way of documentary evidence to aid our understanding of the details of the programme development here. What is clear that the Fort Halstead personnel were responsible for developing the ball of conventional high explosives and associated detonators which would produce an implosion to trigger the plutonium core and create a nuclear explosion. ln particular, they developed the electronic detonators which had to work simultaneously to detonate the bomb's 32 explosive lenses. As always with development programmes of this era different and often distant sites were responsible for research, development, manufacture and testing of the different
component parts of weapons systems. The Royal Arsenal, Woolwich (London) was responsible for the main conventional explosives work with test assembly and firing at the AWRE Foulness range (Essex) where work on the live explosive lenses also took place. The ballistic casing was developed at the Royal Aircraft Establishment in Farnborough (Hampshire).

The casings were mostly manufactured by Hudswell Clarke and Co Ltd, Leeds (Yorkshire). Percival Aircraft, Luton were involved with the design of the sphere that contained the high explosive and fissile components. lnternal electrical components were made both at HER's Woolwich Common factory and by private companies. Ballistic trials took place at the Orford Ness range (Suffolk) in the late 1940sand early 1950s, dropped by the RAF, with further assembly of inert trial rounds at the nearby RAF Woodbridge.

From inception there was very close co-operation between HER and the RAF with Squadron Leader John Rowlands heading the RAF team of ten involved with the atomic bomb's development. His role was to understand the science and engineering and thus guide the RAF in its future storage, maintenance and operation of the bomb and, of course, to ensure that it was developed to the satisfaction of the Air Ministry. Rowlands, with Squadron Leaders Brown, Mitchell and Skelley and Flight Lieutenant Blythe were responsible for the weapon's assembly. Squadron Leaders Betts and Pulvermacher worked on the electronics, Flight Lieutenant Mercer on explosives, Wing Commander Hunter-Toddy joined the mathematics team and there was also a general duties officer.

ln terms of the Fort Halstead HER personnel, Leonard ryte was in charge of electronics and high speed measurements with John Challens leading the electronics team, assisted by Bernard Hillam and Edward House, and leuan Maddock had responsibility for high speed measurements and testing the detonators. Klaus Fuchs was also a contributor in the early years of work at Fort Halstead although he was based at AERE Harwell (oxon). An emigre German scientist, he had previously worked on the US Manhattan Project so came to Fort Halstead to share his knowledge of that programme. However, he was subsequently discovered to be a Soviet spy.

For both safety and secrecy, some of the atomic bomb work took place within the fort. Britain exploded her first atomic bomb on the Mont Bello lslands, Australia on 3 October 1952, known as the'Hurricane'trial. Rowlands and Mitchell from the RAF team transported the radioactive components from the UK and with William Moyce from the HER team assembled the test device which successfully detonated. The following year Rowlands took command of RAF Wittering's Bomber Command Armament School, the first recipients of atomic weapons. Bomb stores at RAF Wittering associated with this deployment are currently under assessment for listing.

Atomic weapons research and development continued at Fort Halstead until 1955 when staff were transferred to a new Atomic Weapons Research Establishment at Aldermaston in Berkshire. Since the mid 1950s Fort Halstead has continued to operate as a government defence research establishment but concentrating on explosives and other research.

No design drawings have been located for e14 and it is not shown on aerial photographs of April 1947, indicating that it was built subsequenly, but is visible on photographs of May 1952. The dates on the memorill plaque on the west wall are curious, as work could not have taken place in this building as early as 1946 as it had not been built at that date and indeed Penney was not appointed until May 1947, yet he unveiled the plaque.

Q14 was a purpose-built structure designed for the assembly of the prototype warhead and its ballistic casing: it was central to Rowland's task to ensure that all the component parts fitted together in the casing. lt was the only place where all the component parts of the bomb were brought together and where a complete model was assembled, although inert model wooden replicas were used instead of the live explosive components. (The colloquial name for Q14 was the 'RAF Building', illustrating the close collaboration between Penney's team and the end user, the RAF.) lt is not known where the electronic components of the trial devices, which were then taken to RAF Woodbridge (Suffolk) were assembled although Q14 is a possibility.

SOURCES:
Published sources:
Cathcart, Test of Greatness. Britain's struggle for the atomic bomb (1994),
London: John Murray
Clive, R, Fort Halstead: a celebration of the first 100 years (1977). Defence
Evaluation and Research Agency, MOD
Cocroft, WD, Fort Halstead, Dunton Green, Sevenoaks, Kent: a brief
assessment of the role of Fort Halstead in Britain's early rocket
programmes and the atomic bomb project (2010). English Heritage
Research Department Report.
Hamilton-Baillie, J, 'London's Victorian Forts', Country Life, Nov 13 1986
(1986),1560-2
Smith, V, 'The London Mobilisation Centres', The London Archaeologist,
Vol 2, No 12 (1975),244-248
Winn, H, The RAF Strategic Nuclear Deterrent Forces: their origins, roles
and deployment 1946-1969: a documentary history (1994). London:
HMSO, 94
Unpublished sources:
Barker, L & Pattison, P, North Weald Redoubt, Essex (2000), RCHME
report, available in the National Monuments Record (reference TL 50 SW
10)
Griffiths, N, R.A.R.D.E. Fort Halstead: a short history (1984). Unpublished
report.
Waterman Energy, Environment and Design, Fort Halstead, Kent: Heritage
Assessment (2009). Draft unpublished client report of 29th June 2009.
National Monuments Record:
Aerial Photograph (October 1946): RAF CPE UK 1789 11 Oct 1946, frame
4473
Aerial Photograph (April 1947): RAF CPE UK 1982 11 April 1947, frame
1110
Aerial Photograph (May 1952): RAF 540/731, 15 May 52, frame 4075

REASONS FOR DESIGNATION :
Building Q14, Fort Halstead is listed at Grade ll for the following principal reasons:

* Historic interest (personnel): of considerable significance nationally for its association with William Penney, Chief Superintendant of Armaments Research, who led Britain's atomic bomb development programme here and which association is celebrated by a memorial plaque;
* Historic interest (bomb development): the only building nationally where the prototype bomb was put together and thus instrumental in the detontaion of Britain's first atomic bomb in 1952;
* Form and design: purpose-built for Britain's atomic bomb development programme. Although a functional building without architectural embellishment its form expresses the secrecy surrounding the programme, being blind on the public-facing side, and which retains its original workshop space and support accommodation for the assembly of
the prototype warhead and ballistic casing;
* Group value: for its associations with Fort Harstead and the contemporary buildings within and outside of the mobilisation centre which were also part of the atomic bomb development work.


In 2009 there was a desk based assessment done by Waterman, on Fort Halstead, west of Otford. The aim was to inform on future heritage management descions for the site at Fort Halstead, which is mainly 20th century structures, and to assess its archaeological potential. (1)

English Heritage, List of Buildings of Special Architectural or Historic Interest (Map). SKE16160.

English Heritage, 2001, Cold War Monuments: an assessment by the Monuments Protection Programme (Unpublished document). SKE17446.

Sources and further reading