Welcome to the historic home of British Defence science & technology

The vision of this website and the future heritage centre based at the leafy and once secretive site in Kent is to preserve the defence and security legacy of Fort Halstead for future generations, independent of any current UK Defence organisation. As such, it is hoped that paid memberships, charitable donations and digital archive sales will support the activities of this unique organisation.

Fort Halstead Trust, 2021

When did it all begin?

2021
1945
1915
1895

2021

The Fort Halstead Trust was formed on 01 January 2021
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1945

The end of the Second World War
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1915

A laboratory was built inside the Old Fort in 1915 for the inspection and maintenance of ammunition stored within the magazines inside the Fort. It has been modified since then, and for a period time in the 1920s after the Fort was sold it was home to the retired Colonel owner.
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1895

Although the precise date for the building of Fort Halstead cannot be fixed, it can be safely put between 1895 at the earliest to 1897 at the latest. Fort Halstead was by far the most expensive of all the forts constructed with the site costing £2,939 and the works £22,354.
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A brief history of Fort Halstead

Constructed some time between 1894 and 1897 as one of thirteen mobilisation centres intended to protect London in the event of French invasion, the early years of Fort Halstead (also known as Polhill Fort and the fort at Knockholt) were thankfully quite benign. While the Napoleonic threat had declined by the time the forts had been completed, interest in the London Defence Positions was rejuvenated during the First World War when the fort was updated, but never fully armed. It didn’t take long after the war for the fort to be sold off in 1921, but this private ownership was to be relatively short lived.

The fort was constructed by a group of Navvies; unskilled manual labourers, supervised by officers from the Royal Engineers. The wooden hut in the background appears to have been a temporary store that was later demolished following the competition of the fort (National Archive COPY 1/416/18)

The most interesting period in the history of Fort Halstead took place in 1938 when the site was brought back into War Department ownership as the Projectile Development Establishment. This saw rapid development on the site with specialist buildings for the development and manufacture of explosives and rocket propellants, as well as the plethora of support buildings to support the thousands of workers. During this phase were constructed some remarkably unique buildings, now scheduled monuments that will hopefully be restored and open to the public.

The detonator laboratory constructed in 1947. One of the many unique buildings on site that have now become scheduled monuments.

Having survived the Second World War relatively unscathed, the site continued to be the centre of British high explosive research, with the decision to develop a home grown atomic bomb under the convenient codename of ‘High Explosives Research (HER).’ The main role of the nearly 1,000 strong team was to develop a series of highly accurate explosive lenses and detonators, essential for reliable detonation of the plutonium core. This immensely challenging and precise work required both electronic and explosives experts to develop new and novel techniques for the production of a synchronised detonation wave, but also for test methods to evaluate their work. Almost all of the unique buildings and chambers constructed for this purpose still exist.

The atomic weapons work transferred from Fort Halstead to the Atomic Weapons Establishment (AWE) in 1955, but the site continued to be a major establishment under the auspices of the Defence Research Agency (DRA), Defence Evaluation and Research Agency (DERA) and more recently the Defence Science and Technology Laboratory (dstl) and QinetiQ.

As the site is finally sold off and redeveloped, the heritage centre will remain. Contained in the original caretakers cottage on site. The humble building will remain as the focus for the Fort and houses a growing and unique collection of items from the unique and special past of this site.

A more detailed history on the origins of the Fort Halstead can be read in an article here.