MrsP has just bought a VW Polo R line, 1 year old, 2600 miles only. £10,000 less than the forecourt price of a brand new one. She seems happy with it after the test drive. They seem to have a good reputation.
When possible I have tried to buy nearly new/ex demo cars. It was always drummed into me that if you buy new then you kiss goodbye to X% purchase tax the moment you drive out of the showroom.
When i worked for the national company (part of Shell) there were approx 20 reps and managers. We used a 'finder' company that would scour the country and source the appropriate nearly new vehicles. We never had problems with any vehicle.