I dont think all historics are exempt, for example my 71 bus is, but a similar age crew cab pickup or van isnt, not London anyway, Ive been looking for a way to carry on getting to work come nex August when the ULEZ is extended and my t5 becomes a £12.50 per day charge, ive looked a commercial bays, commercial T25's, even old Bedfords, Sherpas or Transits, none of the reg's ive put in are exempt. Im looking at an older estate now, assuming they dont change the Euro standards required, currently 4 for petrol, and 6 for diesel. If I cant make it work, i'll have to move or close my business. Sucks because I'd only just invested 9K in a new VW engine, turbo, intercooler etc for my T5, 2 months before it was announced that ULEZ was being extended. I really dont think the powers at be have any idea what these decisions mean to the regular Joe trying to keep their heads above water.
If a historic vehicle isn't showing as exempt it's an error on the system or its not registered correctly. And ALL historic vehicles are exempt, even commercials. I used to have a classic 1978 mk2 Transit and that was registered historic and was ULEZ and CAZ exempt. And I know all the classic Transits on the mk1/mk2 forums were. I've always said I'm surprised someone hasn't started a business selling restored mk1 and mk2 Transits for use for businesses in the CAZ/ULEZ's.