My Action Stations Vol.8 tells me that Wisley was discovered by accident by Mutt Summers (Vickers Armstrong test pilot) who had to make a forced landing and "found an open space behind the woodland that fringed the A3 London to Portsmouth road and which was only three miles from from the Vickers Armstrong factory at Weybridge".
"Two or three years later the site was surveyed and work was started to develop it into a relief airfield for the nearby factory. Wisley came into use in 1943 as a grass airfield and was used for the the remainder of the war".
It apparently closed in 1973 by which time it had sprouted a 7,500 ft runway.