Thanks for all the replies guys (and gals?).
I do have one of my old national licences so that should do for documenrary evidence, and I've had a full road bike licence since 1981 so I should at least make Intermediate National if it doesn't.
Most likely class A it is then. Sorry Chris! Anyone know of a class A bike for sale? (Or interested in a swap/px for a nice 750 Paso?)