Second World War floodlight base, 'Hobblesfield', Great Leighs (EHER 20999)

Partially destroyed. The site of a Second World War floodlight and generator building, which can be seen in an aerial photograph taken in 1960. 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 2006, the concrete floodlight base remained and it is not known if the generator building has survived as a shed occupies the site, perhaps built on the base. This floodlight is one of six concrete bases to survive.

February 2006. World War Two Defences in Chelmsford survey: site visit and desktop research. 'Hobblesfield' is a house on the north side of Dumney Lane, at Hornells Corner, Great Leighs. An aerial photograph taken in 1960 clearly shows the circular base of an experimental 'floodlight' in the rear garden. The base of its generator building can be seen a few yards away to the north-east. <1> In 2006, the floodlight base still survives. Typically, an annular ring of concrete 5’ across, 45’ circumference from its outer edges. The brackets and bolts which originally held the steel frames in place can still be seen. Now, low earthen banking surrounds the ring with bushes and trees. The centre has been grassed over and a sundial is in the middle, forming an attractive grotto. It is not known if the generator building has survived as a shed occupies the site, perhaps built on the base. <2> Five 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 20978.