Sir George Simpson retired on 2 September 1938, his sixtieth birthday. Who would succeed him? This matter had been addressed as early as 21 February 1936, in an internal minute from J B Abraham, an Assistant Secretary in the Air Ministry, to J A Webster, a Principal Assistant Secretary.

Abraham had ruled out Lempfert and Whipple on grounds of age and ruled out Gold, too, but not on grounds of age, even though he would have been 57 when Simpson retired. Rather, there were misgivings about him. Abraham doubted he had “the administrative ability requisite in the Director of a big department” and commented that his temperament was “rather difficult”. Abraham also ruled out Corless, Entwistle, Goldie, J S Dines and E G Bilham, the five in the Principal Technical Officer grade. His conclusion was that none had shown the all-round scientific and administrative ability a Director needed. Simpson's successor would need to be someone not currently a member of the Office's staff. In Abraham's view, the field of selection was “rather restricted”. Brunt might be a possibility but appeared to “lack the personality and all-round ability which was desirable”. Perhaps the most suitable successor was Watson Watt. He was, Abraham said, “a scientist of great ability and exceptional energy”.