Another option is contacting thewhiskyvault.com as they will give you a price at which they will purchase it, with you having to cover the costs (possibly including duties) to import it back to the UK to deliver it to them. I am selling two Rare and Select bottles of Hillside Glenesk 1969 to them later this summer and the price they offered me was more than reasonable, and only slightly less than similar bottles I could find elsewhere on the internet. Send them pictures and a description of the bottle and any box or other wrapping that may have come with it.

Good luck.