I already knew I had a Mark 5 engine in a Mark4 frame but now it appears I have Mark3 forks and, I suspect, a non Douglas front mudguard. It's got a pointed centre rib and isn't valanced like the rear. I'd be astonished if there's one out there and I doubt there's a source of a pattern one. So can anyone please give me a cross section diagram and measurement tip to tip and width. Pictures would be very welcome!