London is introducing an Ultra Low Emission Zone which charges petrol cars that don’t meet at least Euro 4 emissions standards and diesels that don’t meet the much later Euro 6 (because we have to demonise diesels now). As a rule of thumb, you’ll need a petrol car made after about 2005 or a diesel made after about 2015. An online checker is provided so that you can see if you can drive in without being charged.

That gave me an idea. My car was first sold in London and I know its previous UK number. Would it be exempt if it were still there?

Indeed it would.