That's the Semmence Special, an AC-engined Frazer Nash. There is a photo like this somewhere taken at a Hants & Berks MC Sprint which I think probably was at West Court (near Eversley). They were there firston 15/11/46 and as, by 1947 they were at Great Auclum, I think it has to be 1946 or early 1947. Don't think it's Whitfield Semmence driving so perhaps Leslie Hawthorn? (you know, the chap whose son was rather a good racing driver too).
Later the Semmence got a post-war 2½ litre Lea-Francis engine which I was offered in about 1962 when the owner restored it to AC-power for VSCC eligibility reasons.
