Have contacted trading standards consumer direct line, who pretty much confirmed everything that is in the links above. The salesman now claims to have done the same and is claiming wear and tear, and that he's been told the age and mileage of the vehicle bear testament to this, the opposite of what I was told which is that although a contributing factor, they do not detract from his obligations.
Any ideas on how he could show proof that the fault wasn't there? Crystal ball or time machine?