I think the "Mileage Not Warranted" part is perfect cover when selling a car that is as dodgy as this one obviously is.
If someone bought the car without carrying out an HPI report and later found out the cars "hidden miles" the seller would only have to say "We did say that the mileage wasn't warranted" and then you are in trouble.
If they know the mileage isn't correct (lets face it, if that car had genuine 77k miles they'd be shouting this from the rooftops) then they know what the correct mileage is because traders HPI as a matter of course.
Also, this car will have the dreaded Valeo radiator and has seen a lot of action.
But the fact that the OP uncovered the hidden miles means that this car is to be avoided, at all costs.