Brian Gaff (Sofa) formulated on Sunday :
How will this new extended low emission zone in London affect these older
vehicles? One assumes the charges are applied via apnpr, in which case I
guess if you stuck a new or modified engine in that would not be recognised.

All they can know, is what it says on the registration for a vehicle,
associated with the registration number. If you change the engine,
colour, or layout of the vehicle, you are supposed to update the
registration with the DVLA.