Yes, I think Heathrow House (still there) had worked through a few tenants, including BA, as I recall a continuing problem with telephone crossed lines with a BA back office elsewhere (in passing an aspect of telecoms that has gone completely away). The company took over the whole building some time in the late 1970s, and moved out 10 years later. The building had a substantial "refacing" of the glazed front A4 elevation, including much more rigorous double glazing. Phone number 01-759-6522 I recall (which appears thus to have been circulating uselessly in my brain these last 35 years ...).