I'm only guessing here but if it's a minter then i'd say between £1,500 to £2,000.If it were mine i would put it on Ebay as a classified ad with best offer.I would list it at £3,000 to start with and see what offers i got,test the water sort of thing.
8v's are not as sought after as the others but being a 3 door with 1 owner,low mileage,service history etc it makes it quite rare imo.
Good luck.