Slightly off topic. I get involved in occasional electrical work or assessments of ex Police Vans and Ambulances which when being used as a service vehicle were VED exempt.
Unfortunately a lot of shall we say less than honourable people buy ex service vehicles especially ex Ambulances to knowingly abuse the vehicles previous VED exempt status and I have learnt to avoid those types of (often also non paying) customer!
Interestingly the typical ANPR cameras in police cars never seem to register that a previous VED exempt vehicle which is clearly now being used as a camper, delivery van, burger bar etc might warrant checking because the taxation class is incorrect.
However the online tools related to the ever growing ULEZ zones do seem to be picking up discrepancies with these vehicles so they must use an alternate method as checking data with the DVLA or a 3rd party because, taxation class is, for some really weird reason, not available via the standard DVLA API
It's a bit of a palaver getting the taxation class changed, various forms and a cheque etc to be posted to the DVLA and it takes about 6 weeks
In theory it can also be processed at a main Post Office as well but it is a lottery as to whether the post master knows how to do it.
Ironically and reason for this post is about three years ago when I tried to change my first ex Ambulance to PHGV at a post office in my nearest town I had a choice of one!
The only thing the post master seemed to be able to do on his system at that time was change the taxation class of from a VED exempt Ambulance to a VED exempt Disabled vehicle.
Weird world isn't it!