The 2 photos of the Stratocruiser are defiitely Heathrow not Northolt; Northolt never had a hangar that size!
One of the instructors at the College of ATC, Hurn was an Air Traffic assistant called Doug Shoulder. He was an old stager who had actually worked at Northolt in his early days and told us tales about a BEA captain (Welford?).
One day he was manning the runway caravan and a BEA Dakota taxiied out and stopped to do pre takeoff checks. Cockpit window opened and an arm came out with the fingers in a V sign. Doug stuck his arm out of the caravan window and returned the salute; the Capt then called tower and said , 'Tower, your runway controller is making rude signs at my passengers'!