If you look at google maps of the BA engineering base you can still see the twin rail tracks set into the concrete on which the trolley supporting the aircraft ran, they are visible in Megan's Strat picture. Where that hangar was located and the apron is now a car park, its between the building marked as Vanguard House and the British Airways Global Learning Academy. Back in the mid 70's those hangars were used for the storage of unserviceable aircraft components.