30th June 1953.
I was thinking about my first experience of LHR only the other day, and it has to do with the recent tragic death of Trevor Bailey. On the 30th of June, 1953, Heathrow North Side, I was excitedly waiting with my parents to board a BOAC Argonaut, bound for Accra, Gold Coast (as it was then) for my first ever flight. Outside, the apron had Stratocruisers, DC-6s (PanAm), and I remember being a little bit disappointed when my father pointed out 'our' aeroplane that it wasn't the interesting one with 'the three tails' (Constellation).
When the boarding call came: "Passengers should extinguish their cigarettes and follow the blue/green/...red?* light to embarkation," my father had to be torn away from the knot of people at the bar. Not for reasons of any last-minute 'Dutch Courage' you understand, but they were crowded round the radio set, listening to Trevor Bailey and Willie Watson doing their heroic stand against the Aussie attack in the Lord's Test Match.
The other interesting thing is that, while the engines were being run up, a Comet 1 taxied past and took off, taking the Queen Mother, and I think Princess Margaret on a tour of Rhodesia and Nyasaland.
* There was a series of painted light bulbs in the ceiling, which you followed to reach the correct exit onto the apron, where a BOAC ground girl was waiting with a clipboard to tick your names off on the passenger list. There were three colours. Blue and green I'm sure of, not so sure about red.
The other thing I remember is the Alcock and Brown statue outside the Forte restaurant, and all the chairs being wicker.