Hi Brian
This comes from the Federation of British historic vehicle clubs after consultation with DVSA and is available on their website.The DVSA record shows all eligible vehicles as mot exempt until you tax it when you have to make the declaration yourself.If you do not declare the vehicle as mot exempt when you tax it you will be required to mot it.The only time you can make the declaration is when you tax it. This is to allow eligible vehicle owners a period of grace from when their vehicles became mot exempt on May the 20th to when the vehicle tax is due, after that it's up to you.
Hope to be at Croft for the Nostalgia weekend and would look forward to seeing you there if you are going.
Best wishes
Steve

My bus number (if any): RML2551

Thanks Roy, that's helpful. My bus is on Class 5 now. In theory I suppose they will update the form from 20 May but won't be surprised if that "slips through the net"....

My bus number (if any): RML2302