The gentleman's classes are presently Supertwins O and U, Modern Vintage O and U and Blunderbike.
Formula 40, Superbike, Supersport and ROR are for faster riders. If you make Formula 40 with a GTU and GTO designation, I'll step up to the plate and damn it I'll try my best to at least bring up the rear though I'm thinking formula 50 needs to be an option