www.regtransfers.co.uk, used these before to sell a plate J8 WKD, was on there a good few months maybe just over 6 months, but had a phone call out of the blue with a buyer, i recieved just over 400quid (only said i wanted 200-250 first off), and they did all the paperwork and the replacement logbook mot and tax and a cheque

didnt have to pay upfront was a bit of a slow transaction at first (may have been down to the buyer though) but after that it flew through, cant rate them high enoguh