IIRC the aircraft was actually a waddington aircraft and I have a vague recollection that it may have been Terry Danby's crew, but then that could all be b*ll*x.
I do recall what happened however.
It was normal to do a hangar start, the crew would crew in and do the pre-flight checks up to engine start. It would then be shut down and towed out with the crew still on board. Once outside it would be powered up and started in short order thus minimising freezing time outdoors.
On this occasion the aircraft, fully fuelled, crashed through the concrete floor. IIRC the hangars were the RAF pre-war standard hangars, or very similar, and the sand below the concrete had simply shifted over the years.
The joke at the time was "Any more comments about concrete evidence and I shall . . . "
PS, the shifting sands also undermined other buildings too. There was a multi-story accommodation block on the Mexican side that used to house all the schoolies, nurses etc and in which many hours fun could be had (60s). When I was there in the 70s the block was closed, abandoned and forelorn as it now had the leans and was in danger of collapse.