I note that all comments on Clubmans Racing have been about P3/P4. How about a class for fifties machines up to 500cc capacity. I believe in the era there were true clubmans machines such as Gold Star BSA, Velos, ajs and matchless, and ROYAL ENFIELDS. You can still buy Royal Enfields from India for $5000 brand new. Any P3 class would have to include them at a fairly competitive level, and they could provide entry level into historic racing for the young blokes. I suggest the machine rules should be similar to those of P4/P5 except the capacity limit should be 500cc to prevent use of big triumph and Norton twins. It would gives races similar to 125GP races in which the speeds would be relatively low but you'd really have to ride hard to win. The point is that on a cheap bike you would still have a good chance. I'd buy an Norton International and blow you all off.
If we get really serious about clubmans racing we could combine it with a rally, where you ride your bike to a race track, unplug the lights, fit your number plates and race. I seem to remember this actually happening back then. Now you've really got a challenge!
Perhaps we could get Duttons to sponsor a rally where two hundred idiots on classic motorcycles ride over the Black Spur and up the back way to mansfield and then to Winton and compete in races and time trials. Could even get to ISDT status. Let's see what you're made of!