Isn't their some weird rule where a private seller has to be asked if a car has been the subject of an insurance claim, otherwise if not asked they don't have to declare it? And a trader has to decalre it straight away?
Either way, i'm not into 3 doors as much as I used to be so can't comment on the cost, but with bad history, no mention of service history , I wouldn't be paying more than £7k for it since there are plenty out there with all good paperwork and similar miles for less than the asking price.