Second World War floodlight base, Thatcher’s Farm, Vicarage Road, Roxwell (EHER 20978)

Partially destroyed. The site of a Second World War floodlight and generator building, which can be seen in an aerial photograph taken in June 1946. The floodlight was probably constructed between 1936 and 1940 as part of an experiment to light up the night sky with a grid of large, fixed 'floodlights', as a defence against German bombers. The experiment, termed 'Silhouette', failed as the network of floodlights acted as a navigational aid for the enemy aircraft, and it was subsequently terminated in March 1940. When visited in 2005, the concrete base of both structures remained and embedded in the concrete of the floodlight base was the remains of the steelwork which held the main structure. It is one of six concrete bases to survive.

November 2005. World War Two Defences in Chelmsford survey: site visit and desktop research. An aerial photograph taken in June 1946 shows the clear shape of an extant experimental 'floodlight' standing in a field immediately west of Thatcher’s Farm, Roxwell. Its twelve sides can be seen although nothing remained of the interior mirror structure. The entrance was on the north-east side. A few yards away to the north-west was the surviving base of the generator building. <1> Visited in 2005, the concrete bases of both the floodlight and its generator building still survive. They lie in a small rough meadow. The floodlight base is effectively a ring of concrete, 42 feet across, hollow in the middle. The metal sides of the structure stood on this ring which is 5 feet wide. Embedded in the concrete around the circle is the one inch upstanding remains of the steel. At one side, an open rectangular hole shows where the cables came in from the generator. Nothing survives of the generator building other than its concrete surface. <2> Six photos. <3> During the late 1930s/early 1940s (probably 1936-1940), an experiment was conducted to light up the night sky with a grid of large, fixed 'floodlights', as a defence against German bombers. Each installation consisted of a steel enclosure, 50 feet across, in which the floodlight was mounted, surrounded by twelve large mirrors angled towards the sky. Information on the experiment is still scarce; an enquiry to the Imperial War Museum has been unsuccessful. Enquiries by Mr F. Plume at the Public Record Office (PRO) in 1992/1993 have resolved some of the questions. <4> <5> A map drawn by Mr Plume in 1999, from his earlier investigations, shows 50 sites in Essex, located in an area from Little Leighs in the North to Eastwick in the South. It is not known whether this was the complete grid (although one floodlight is known to have been sited at Dovercourt, EHER 10715) or whether the experiment overlapped to other counties. The experiment was not a success - it is said that the light reflecting from the clouds lit up the countryside as a perfect navigational aid for the bombers, and the work was terminated in March 1940. <6> <7> The project was termed 'Silhouette'. <8> See EHER 20565 for details of the only known remaining example of a Second World War floodlight from this experiment in Essex. Note: This monument is one of six floodlights from the original 50 where the concrete base is known to survive. See also EHER 10715, EHER 20661, EHER 20858, EHER 20875, and EHER 20999.