Just in case it gets lost:
I had a quick look at
https://www.forces-war-records.co.uk/ and see: 180249 RAF 1918, 79293 Flt Lt 1942, temporary Sqn Ldr 1944.
A bit more from Ancestry: born 6.8.1900 Egham, father Alexander Dallas Brett, solicitor (!), mother Ethel Mary. 23 Station Rd, Egham. Baptised 3.9.1900, Egham, St Johns.
There is more about his family, if you want it. Also copies of his Aviator's certificate (and photograph), number 8319 dated 1.7.1928 at Cinque Ports FC on DH60X.
He too was a solicitor, like his Dad.
If you want any of this let me know.
Laurence