I believe that I have now found the answer. There is a surname and initial on the label of the trousers (which incidentally is different to that on the tunic). Having cross-checked this with entries in The London Gazette for AAC officers who were awarded GBE/KBE/CBE/OBE/MBE, I found a match. Moreover, after digging a bit further on Ancestry, I found out that his father also served as an officer with the AAC. Actually, both father and son were initially commissioned into the Royal Artillery and then transferred to the Army Air Corps; retiring as full Colonels.
As such, the Army Flying Badge most probably belonged to the father, who probably served as an Air Observation Pilot (or perhaps in the GPR before being commissioned). The tunic may have belonged to the father as well. Certainly, the trousers were tailor-made for the son.
What would be good now is to find a set of full colonel's shoulder boards, to complete the tunic.
The career path followed by father and son was as follows:
Father
- Commissioned Dec 1944, Royal Artillery
- Royal Aero Club aviator certificate 1947 as "qualified service pilot"
- Mentioned-in-despatches Jan-Jun 1949, Malaya, Capt, RA
- Awarded Military Cross Feb 1950, Malaya, Capt, 26 Fld Regt RA
- Promoted 1958 to Maj, RA
- Transferred 1959 from RA to Army Air Corps
- Promoted 1967 to Lt-Col, AAC
- Promoted 1971 to Colonel, AAC (Commands & Staff)
- Retired 1974 as Colonel, AAC
Son
- Commissioned 1976, Gen List
- Promoted Mar 1978 to Lt, Royal Artillery
- Promoted Sept 1982 to Capt, RA
- Transferred Sept 1987 to AAC
- Promoted 1989 from Capt to Maj, AAC
- Promoted Jun 1996 from Maj to Lt-Col, AAC
- Awarded OBE Jan 2004
- Retired May 2012 as Col, AAC