I was just once, some years ago, inside the restaurant of the westbound Heston services (which I pass regularly) and noticed they had a number of good photographs of the airfield from the 1930s up on the wall. Don't know if they are still there.
The services date from the 1960s and the eastbound side is still the original one. The westbound side was destroyed by fire in the 1980s and rebuilt to a completely different design. The photos were maybe added after the rebuilding.