Maybe it's because it was deemed OK to show disused aerodromes such as Broadwell and Akeman Street (near Leafield), but not active ones?
Maps of the period often just include the word 'airfield' and that's about all. One step up from 'Here be dragons', I guess?
I wonder whether the PIs had a suitable bunch of anonymous countryside photos which they just snipped into shape and stuck over the actual imagery? The aerial map of Keevil looks rather odd, for example.