Forget Norton, but it seems to me that the sides of the tank are actually curved, and you can just make out a logo that seems to be 3 letters, BSA is first that comes to mind,but there were others such as AJS, NUT. Not sure either would fit here.
Cycle stem handle bar fitting; rim front brake, I can't see a gear lever so possibly single speeder? A lot of air under that tank which might be a clue. Side valve engine with exhaust held on by a nut. There is a cable running to the timing gear chest [valve lifter?] same as my Sunbeam but I don't think it is a Sunbeam though.