Shame, but if you'd asked the question in 2004 I'd have had the answer by now because I had the 'as built' drawings for every building built on site / refurbished since the start of the RAF Airfield expansion period (1935/6 IIRC) up to 2004 all of the pre 80's drawings were in microfiche, some on linen, some paper and scanned images and the more modern drawings as cad sat in my office.
The contractor I worked for at the time (Babcock) didn't win the SE Prime contract but did get the SW Prime one, having absolutely no wish to work for the winning bidder I jumped ship to the SW Prime in Dec 2004, returning part time to assist the Prom with the site handover to the incoming Prime Contractor. All drawings etc were left in my old office (EWC) when it went over, rumour had it they didn't stay there for long.