AP you raise an interesting point in your answer at 21.53 Fri. My understanding is that only the Owner has the right to sell a vehicle, NOT the Registered Keeper unless he/she is also the Owner. I've done a C&P below to back this up although I can't vouch for the validity of the site. My daughter is the RK of my car and I would have some very strong words with her if she were to try and sell it although she would probably succeed as I would bet the majority of people think the same as you. If I'm wrong then please show me the evidence.
I apologise to the OP if this is slightly off topic. Perhaps I should have started another thread.
"Who is the registered keeper?
The registered keeper is the person whose name appears on Section 5 of the Registration Certificate of the vehicle (also called the log book, V5C). That person is responsible for taxing the vehicle, doing the MOT and maintaining it in good condition. Traffic violations like parking tickets and speeding fines will be sent to the registered keeper as well.
Who is the legal owner?
The legal owner is the owner of the car, that is, the person who has a legally enforceable claim to the car. That person has the right to sell the vehicle while the registered keeper is not in a position to do that (if registered keeper and owner are different that is).
Most of the time, the legal owner and the registered keeper will be the same person. However in cases where a car is leased, then the legal owner will normally be the company and the registered keeper the employee who uses the car. Another example is when a father buys a car for the son to use - the father may want to retain all rights to the car but give the responsibility of day to day running to the son.
Car insurance
Most car insurance companies will insist that the policy holder be the registered keeper to keep things simple and will not quote for cases where they are different. By law, the policy holder does not need to be the registered keeper but you will be narrowing your choices of insurers if you are in this situation. This is mostly to do with the fact that many experienced drivers used to put down their name as the policyholder while a younger driver would be the registered keeper so that they can get cheaper car insurance. Of course insurers have thus cracked down on this approach because it's fronting and have therefore insisted for both policy holder and keeper to be the same."