Winseer:
If every camera around London now had APNR on it - then an outside driver for a large haulier treking inside the A406 would get noted at the first camera, and their outside yard fined.
What I’m thinking might actually be happening, is some bods are half-watching passing trucks on a camera, assume that those going through the restricted area are “of the local depot” for that particular firm, and not giving them a second look.This would allow every yard sending wagons into an inside-406 branch - pretty much free rein as to where they go.
I did a job on agency that involved taking stuff to Enfield (inside M25, outside North Circular) dropping the trailer there, and then picking up an Enfield trailer, and carting it to some other depot inside the A406, tipped, return to Enfield, dropped, and then my trailer back to the Kent depot later on.
Now the “secondary” trailer has got the Bronze sticker on it - but the tractor doesn’t! It’s the same one right the way through the shift! SO… The number plate being picked up by APNR is going to be the same “Unauthorized” outside one surely■■? Neither my tractor or first-leg trailer have the bronze sticker on them…
Is there a “Fleet” arrangement, a “Depot” arrangement, or does the Bronze thing mean nothing at all now?
I think it goes pretty much un-policed to a large degree. Even if they had bods making notes and taking pics - if my understanding is correct, they would have to deal with the issue of the starting point… which could have been inside the restricted area. Admin heaven 
Me pointing to ANPR, should probably have been ‘could’ rather than ‘should’.
I think where it is more likely to be flagged up - is if residents in a specific area started complaining about the restriction being ignored. And maybe The City itself.
We can only guess.
London Roulette?