Originally Posted by
DaveReidUK
The terminal, and main apron, were to the north of the parallel taxiway, with a smaller apron to the south.
While idly perusing Google Maps' aerial view of the current Heathrow, I was delighted to discover that the southern part of the original apron (top centre of the photo, with what looks like a lone DC-3 parked) is still intact, as is the taxiway that used to connect it to the runway.
The current Northern Perimeter Road runs along the line of the old parallel taxiway at that point, and the apron is the tarmac area roughly opposite the Renaissance Hotel's main car park.