Nota Streamliner #1 aka Mazencarb!
That's right, yes.
I was just looking back at my records to answer the previous 2 posts and was about to reply and add another question (who built the bodywork) but I've missed the chance now as you've given me what I asked for!
The engines of these cars were British but could be Standard 10, Ford sidevalve, Hillman Minx, BMC 'A' Series or Coventry Climax, and I have no idea which one of those this example has! It is the Mazencarb No. 1, which was named after a well-know overhead-valve conversion at that time.
The body was built by British ex-pat Jack Wiffen, whose main claim to fame was building the body for Donald Campbell's Bluebird record car.
So it's solved and a point to PJ.