Flint received his medical education at University College Hospital and qualified MB BS in 1950. After house posts at University College Hospital and a lectureship in anatomy at University College he gained his Fellowship in 1957 and was surgical registrar at UCH and orthopaedic registrar at the Royal National Orthopaedic Hospital. Thereafter he specialised in plastic surgery and was senior registrar at the Mount Vernon Plastic Centre at Northwood. He emigrated to New Zealand where he was the senior plastic surgeon to the Auckland Hospital Board and continued practising in Auckland. He died on 24 January 1993.