If one is [briefly] talking about MoD properties, think of the plethora of buildings that, post-War, remained under the Defence banner for MANY decades.
Old War Office, Adastral, Northumberland, Kelvin, Lacon ... there were squillions of them!! And thats only from an RAF perspective!
Now think what that sort of office space would have cost if purchased post-War. No wonder the Services hung on to what they had [conveniently] acquired!!