Bit of a punt, and it may of course not be your man, but by playing around with the London electoral rolls I've found one Dennis Hamilton Tindall, born 26 June 1910, who lived in Hampstead and was in business at 8 Henrietta Street in Covent Garden. This - coupled with his marriage certificate, which says he was a publisher - would mean he was one of the family which owned the medical publishing company then known as Bailliere, Tindall & Cox, later simply Bailliere Tindall.
He doesn't seem to be on the 1939 Register, but given his age I guess it's likely he could have been in the forces by the end of September 1939. His wife Ursula (née Orange) is on the Register, but at her parents' home in Uckfield.
Dennis remarried after Ursula died in 1956 and passed away 29 October 2007 in Billingshurst.