AARON O'DICKYDIDO,
They were built for the RAF, Prefab no less, built as a short gap, still being used, asbestos and all! There are quite a lot of 60's era semi's built as AMQ quarters that have garages attached, there were some at Driffield and I have seen them at other camps.
As I said, there is no standard though and it, as today, depended on budget and year built.