London's BulwarkIn September 1940, as the Battle of Britain began to turn into the Blitz, England's leadership looked to the defences of London. Air Vice Marshal Keith Park, head of The RAF's 11 Group, defending London, described the North Downs and the hills of Surrey as 'London's Bulwark against the Luftwaffe', prompting the local slogan 'Bulwarks to Hitler!'.
The SperryThe 7th Anti-Aircraft division, spread across north Surrey including Croham Hurst and Addington Hills, was the first to test the 'Sperry' fire-control system, a mechanical computer which predicted the arrival of enemy planes. Surprisingly, it was on Croham Hurst that the first Sperrys were deployed, linked to a battery of the new QF 3.7 inch gun. The Sperry gave us a wartime song that ended:
I love to work a Sperry
While bringing down a jerry
It's foolish but it's fun!
The Sperry was mounted in a bunker about where the Friends of Croham Hurst Woods bench on top of the Hurst stands now, but nothing is left of it. Unfortunately there don't seem to be any photos of the battery in action, but here's a picture of a similar unit from the 7th Division in London:
Despite the Hurst's excellent view of approaching night time formations, the site was considered 'cursed' by the troops and was the target of highly effective bombing from the Luftwaffe. Several observers stationed on the hill by night in 1940 went missing, and in 1941 a single bomb struck the top of the Hurst and destroyed half of the 4-gun battery that was mounted there. So unpopular did the site prove that from 1941 it was abandoned, and no sign is left now of the Hurst's part in the war except for a single bomb crater (now with trees growing round it) at the west side of the moorland.