Looking in this months Glass guide book the car books at:
£8,875 @ 59k Miles Trade Price
£10,275 @ 59k Miles Retail Price
Retail price is for a main dealer so private will be less.
When you adjust it for the high mileage it reduces it by -£1675 so correct value is:
£7,200 @ 100k Miles Trade Price
£8,600 @ 100K Miles Retail Price
But as a trader realisticly I would say trade in for £6,000 and sell private for £6,990.