Realistically you would get around £550 at auction, hammer price. Given most of the big auction houses, who attract the biggest buyers, charge 20% commision you may walk away with around £440 in your pocket.
I know one shop has one for £1750. A lot of the shops that deal in rare, discontinued bottlings tend to at least double or tripple the highest auction results or just make up a price.
Since you are in scotland, the Bonhams Whisky Sale 14th Dec will be accepting entries.
Good luck with the sale.