It doesn't half look similar to this car to me, which is described as a 1952 Cunningham C3 Special currently For Sale in the UK...:
Yes! I noticed that and I've begun investigations. The story about the unbodied C3 cars is correct, and it could well be that the Gomm body was fitted to this after it was on the Alta, or Gomm made 2 bodies. Mind you, that style of body was pretty generic at the time.
The puzzle car took me a long time to solve - I knew the photo was Deers Leap at Oulton Park, but the entry list for the Gold Cup meeting didn't have a 50s sportscar race. Of course, the car does not date from the 50s, but is a recent recreation of a 50s-style car. It was racing in the FISCAR event - the 50s sportscar racing club have a series for GT and production sports cars of the type which raced in the 50s, and must be to period spec. Quite how this car complies is beyond me, but it's nice to see it racing. (Also in the same race was a recreation of a Cunningham C4R - not a production car at all!)