BM BCh Oxford 1943, DM 1953; DCP Lond 1949; FRCPath 1968.
Garrett was senior registrar in pathology for United Sheffield Hospitals before being appointed consultant pathologist in haematology at Selly Oak Hospital, Birmingham. Garrett was later appointed consultant haematologist at Christie Hospital, Manchester, a position he held until his retirement in the 1980s. Garrett was a member of the Association of Clinical Pathologists and the British Society for Haematology.