G-AGYX was one of the longest serving Dakotas with BEA, from being transferred over from BOAC when the airline was formed in 1946, it lasted to 1961 when it was sold to Autair. I think I can just make out the BEA "Key" logo of the era on the nose.
BEA ran quite extensively from Northolt into the 1950s, progressively making the transition to Heathrow, starting with building hangars there, as larger aircraft were delivered. The Dakota and Vickers Viking ran mainly from Northolt, and only as the Airspeed Ambassador and Vickers Viscount came along in the early 1950s were operations started from Heathrow.
Pan Am never operated from Northolt (well, once they did
); whether that is a stock shot I can't say. The BEA hangar at Heathrow was demolished in 2007, here it is being knocked down. The upper fascia where the initials were has gone but you can relate to the rest
https://forum.keypublishing.com/show...ase-demolished
The first picture has got, just peeking into the left hand side, the rear of one of the special BEA buses which ran from Central London to both Northolt and Heathrow, new in 1953
1953 AEC Regal IV - BEA Coach 4RF4 MLL740 - London Bus Museum