Thanks Gerwyn, great links. My father was a great motorcycle fan and rider, but having had a couple of bad accidents on his bikes I was banned. So when he talked about people like "Flying Freddie" it was more likely to be his time tuning Riley's, rather than his motorcycle (and side-car) exploits.
I'm still going to Google for a book on these prewar guys, as they certainly had massive something or others!
Cheers
B