I suppose I should have been more specifc. Where we used to walk (and I think it is the Duke of Northumberland's River) we crossed one river and walked between them, probably via a bridge which still seems to be there near the junction of Bedfont Road and Long Lane. they certainly were in Luthansa colours and there was sometimes one and sometimes two and these little walks (with my Uncles dog) were about 4.00 pm on a Saturday afternoon, I assume about 1963-64.
There was nothing between the southern peri road and the central building in those days (except grass and 28 L) and the C-46s were parked in clear view.