It's true that the V5C is not proof of ownership. It's also true that DVLA will do everything to distance themselves from getting involved in a dispute of that nature. However, they should at least, be able to give you the date on which it changed registered keeper. As Harry Bllomfield says, they are obliged to respond to a reasonable request, but I would suggest that it would need to come from a lawyer on their letterhead. They need to ask for "a copy of the vehicle record". That should basically get them everything the DVLA holds on the car. Depending on how old it is, some of it may be on microfilm, and DVLA's response times are awful at present.
I take it you've been on the gov.uk website to check that it is taxed and MOTd currently?
Also check if it is insured:
This won't give you the answers you were looking for, but a few more bits of the jigsaw, maybe?
I take it you've been on the gov.uk website to check that it is taxed and MOTd currently?
Get vehicle information from DVLA
Check a vehicle's details, tax and SORN status and expiry dates on the Driver Vehicle and Licensing Agency (DVLA) database - online and telephone enquiries
www.gov.uk
Also check if it is insured:
askMID
www.askmid.com
This won't give you the answers you were looking for, but a few more bits of the jigsaw, maybe?