Trying to summarise Jeff Jefford's paper on pages 91 to 94 of
https://www.rafmuseum.org.uk/documen...ary-Forces.pdf - There was a review of aircrew requirements in 1953 which decided that aircrew reinforcements in time of war, would be provided from the reserves, but they needed "realistic, that is to say operational, refresher training at a level of sophistication far beyond that which could be provided by Chipmunks and Ansons at an RFS... In fact, because of the already reduced size of the VR, the Air Council had decided to start running down the RFSs, even before Baker-Carr presented his findings. In a statement to the House in December 1952 the Parliamentary Under-Secretary of State, George Ward, pointed out the increasing irrelevance of continuing to fly RFS Chipmunks and Ansons off grass strips in the jet age at a cost of some £2.5M per year and he announced that seven of these units were to be closed."
This evidently led to the cull in 1953 mentioned by Dora; it's not so much pre-Sandys in terms of unmanned aircraft but certainly part of some serious thinking about how the RAF and its reserves would be shaped ready for the next war. Incidentally, Sandys was appointed Minister of Defence in January 1957 and the infamous White Paper was published in April, so Sandys would have had little input. He may have wielded the axe, but it was sharpened by Macmillan (Chancellor before becoming PM in 1957) and the Treasury.