This is from a diffferent forum a few years ago about the same thing....
If you send off the paperwork requesting issue of a V5, DVLA will write to the current keeper (if any). If they don't respond within (IIRC) 2 weeks then a V5 will be issued to you.
This will make you the registered keeper (with all the associated legal responsibilities), but not the owner.
If you appropriate the vehicle - ie move it, start driving it - basically exercise any property rights over it, but do so honestly, it will not be theft. The Theft Act 1968 specifically states that you are not in law dishonest if you:
honestly believe you have a legal right to, or
believe the owner would consent if they knew of your appropriation and its circumstances, or
believe the owner cannot be found by taking reasonable steps.
Making all reasonable enquiries to locate the owner and get their permission would therefore stop you from being guilty of theft. DVLA will sell you the current keeper details, for a lawful purpose - you can download the paperwork off their website.
This is NOT the same as making you the owner. Very little in English law will transfer genuine title away from a previous owner without their consent. Which means that if someone does turn up in future, claiming to be the owner at the time you took the abandoned car, chances are you will have to return it to them, despite any money you may have spent on it, so be warned...
Obligatory disclaimer - I am not a lawyer (any more!)
Tol
PS (edit)- Thinking about it, of course, it being a conveyance, you'd have to avoid the TWOC offence too. No legal requirement of dishonesty, but a statutory defence of either:
believing you have a legal right to take it
believing the owner would consent to the taking if they knew of it and the circumstances
NO defence of believing the owner can't be located with reasonable steps...!!
I guess the gamble is if the guy responds to the DVLA saying - yes it's mine. Then you would have no choice but hand it over.
But...there's a better way.
If the carpark has the right to scrap it - then they have the right to take ownership of it for disposal.
Assuming there is something owing for a years parking....make the company an offer.
The company seizes it and disposes of it in your direction. You're covered. You'll have a paper of ownership from the carpark company.