In addition, my experience associated with strategic maritime facility upkeep suggests that by the time the facilities have been 'acknowledged' by MOD to be unsustainable/unaffordable, said facilities have been so for a long period of time.
As has been discussed on many threads, the Abbeywood chaps can be a little tardy in making decisions, and quite good at ignoring the inevitable, so by the time comes to close something down, it is hardly a surprise that the company does so quickly - they have normally been subsidised by the contractor under good will alone pending a decision.
Why should a company take their time when it costs their money ? How long it exists is irrelevant.