So if the licence was sold by the previous owner in January 2008 and the licence surrendered, there is nothing amiss if the car still has a date of liability from that date (other than the fact that the dealer's profit margin has probably now depreciated out of existence).
If they use the vehicle on a road other than on a Trade Plate i.e. on any Excise still in being or if still in their posession after 3 months then they have to notify change of ownership. In doing so they become the Keeper on the Register and SORN rules aplly to them.
Thanks for the link DD. Only just noticed your reply. Putting in some of the cars from the big place in town that I visited a couple of weeks ago shows their stock to have a very long period standing. No wonder the owner was knocking 25% or more off loads of cars to try and move some stuff.