[isostatic]

> The issue here is that obviously you have to prove that those miles were done in United Kingdom

Why? The law could just charge based on miles regardless.

However if you did choose to allow people to exempt overseas mileage you could read the odometers at ports (say charge them £10 for the privilege, so it only makes sense if you're doing a lot of mileage)

Clearly Northern Ireland would have to be exempt.

However mileage is very different, the externalities of a smart car driving 50miles from Lancaster to Carlise at 3AM is far different to that of a 13 ton lorry driving from Luton to Oxford Circus at 8AM -- in pollution generated (locally and globally), in damage to the road, congestion