My 1964 Singer Gazelle is compliant and exempt from the charge. My 2001 Peugeot 406 is not. Not that I would ever drive to London, but I wonder if there's an exemption for 'classic cars'?
AFAIK, there is an exemption; over 40 yrs-old cars.
................compliant and exempt...................
A vehicle can be "exempt", yet be non-compliant with one or other requirement for exemption.
e.g. a shoite-spewing charabanc could (would?) be exempt by virtue of its "classic" status.
If the rules were on emissions alone, it would (may?) not be.