I think the film you mention (set in WW1) was made in a field about a mile west of Wisley, as I remember seeing a huge marquee (like a circus big top)near the parked WW1 aircraft when I flew over. The aircraft were based somewhere to the north of London and seemed to 'commute' every day round the west of the Heathrow zone. The one I'm thinking of was set in WW2 and they built a mock town on the runway; something like 'Hope and Glory' I think it was called, but it would have been '86 'cos I was flying out of Fairoaks then and I remember re-joining via Wisley/OCK and seeing the set.