Fort Halstead Fort Halstead is a research site of Dstl , an Executive Agency of the UK Ministry of Defence . It is situated on the crest of the Kentish North Downs , overlooking the town of Sevenoaks . Originally constructed in 1892 as one of a ring of fortresses around London , Fort Halstead was to be manned by volunteers in the event of a crisis . The base went on to become home to the Ministry of Supply , from which it became the headquarters of the Royal Armament Research and Development Establishment ( RARDE ) . History of RARDE . Two departments , the " Research Department " and the " Design Department " , were established in 1922 at Woolwich Arsenal . During the Second World War , the Design Department moved to Fort Halstead , followed by the Research Department . It is believed that Britain ' s development of the atomic bomb , hidden under the name High Explosive Research ( " HER " ) was initially based at Fort Halstead , where the first atomic bomb was developed under the directorship of William George Penney , who had been appointed Chief Superintendent Armament Research ( " CSAR " , called " " Caesar " " ) by C . P . Snow . " Operation Hurricane " saw the bomb conveyed by frigate to Australia and successfully exploded in the Montebello Islands . In 1950 , it is thought that the " HER " research was moved to a new site at Atomic Weapons Establishment , Aldermaston in Berkshire . In 1955 , the two departments were merged to give the Armament Research and Development Establishment ( ARDE ) , which was granted the title " Royal " in February 1962 . In the 1980s , RARDE was amalgamated with the Military Vehicles and Engineering Establishment ( MVEE ) – formerly the Fighting Vehicles Research and Development Establishment ( FVRDE ) – with sites at Chertsey and Christchurch , and the Propellants , Explosives and Rocket Motor Establishment based at Waltham Abbey and Westcott . Following the December 1988 Lockerbie bombing , forensic experts from RARDE ' s explosives laboratory examined material recovered from the crash scene , and subsequently testified as expert witness es at the Pan Am Flight 103 bombing trial . Evolution to DERA . On 1 April 1991 , the Defence Research Agency ( DRA ) was set up by bringing together Royal Aerospace Establishment ( RAE ) , Admiralty Research Establishment ( ARE ) , RARDE , and the Royal Signals and Radar Establishment ( RSRE ) . It was an executive Agency of the Ministry of Defence . Four years later , when DRA was itself merged to form the Defence Evaluation and Research Agency ( DERA ) , the forensic explosives laboratory came under media and scientific scrutiny . In 1996 , amid allegations that contaminated equipment had been used in the testing of forensic evidence , an inquiry was set up under Professor Brian Caddy of Strathclyde University to investigate the laboratory ' s alleged shortcomings . DSTL . Following the split of DERA in 2001 , the Fort Halstead site was given to QinetiQ who leased part of the site back to Dstl . Its most recent principal functions have been research and forensic analysis into explosives , and the site ' s explosives laboratory was again used in the investigation following the attempted 21 July 2005 London bombings . The facility has been the largest employer in the Sevenoaks district , with 1 , 300 personnel working on the site in 2000 . In March 2006 , QinetiQ sold the Fort Halstead site to Armstrong Kent LLP for an undisclosed sum . On 17 June 2011 Dstl announced that its facilities at Fort Halstead are to close following a review of operations at the site .