Chevvron,
I think you will find that it was built to house the Brabazon, hence the very large archways. It had a 230ft wingspan, I believe, if the grey stuff serves me right after all these years. You could put three or more Stratocruisers or Connies in each bay easily. Also VC10's and 707's which were often inside three at a time.
The end of the building from the first floor up was offices and through the center. The ground floor was all workshops and they were very comprehensive in their abilities. Today I expect it is all penpushers!!
Speedbird48.