The absence of BEA aircraft can be noted. They built up quite a substantial operation immediate postwar from Northolt instead with DC-3s and Vickers Vikings, surprisingly the frequencies to the likes of Paris or Amsterdam by the early 1950s were not a lot different to nowadays - much smaller aircraft, of course. BEA were waiting for the completion of the Queens Building. The Airspeed Ambassador's arrival (and very soon after the Viscount) changed things, these were never operated from Northolt, although it was apparently not unknown for their flights to be in the transition years - passengers had reported to Heathrow and were suddenly told the Ambassador was u/s and the flight would now be operated by two Vikings from Northolt; all aboard this bus.
Speaking of buses, note the aircraft in the pictures are all on remote stands. The apron bus contract had been given to London Transport, who used a motley collection on airside transfers, quite separate to the elegant (for their times) new vehicles running from the central London terminals. Some of them were even pre-war. It was however a nice driving experience compared to regular bus routes, so came to the more elderly, most senior drivers, who apparently struggled negotiating the ramp, especially at night, between the aircraft.
The European operators came to Heathrow much earlier, although a few pioneers, like KLM, actually went back to Croydon at the beginning, from 1946. They were handled by a separate BEA team.
Such was the popularity of the airport as a tourist attraction that a sightseeing operation, with Dragon Rapids running 10-minute flights, started from alongside the spectators' enclosure; there have been several posts about the detail of this here in the past, so won't repeat that.
The big Northside ramp west of the tunnel later became the long term car park, not resurfaced, and certainly until the early 2000s had the original concrete surface, looking a bit careworn, with the ghosts of where various flush lights etc had been patched over.