You can buy this bottle at Lochranza Hotel for 65£.
According to the owner of the Lochranza hotel and some locals at the hotel bar this is the story behind this bottling:
The favourite Whiskies of the owner were the old Macallan Oloroso Sherry Cask bottlings. So he asked at Arran distillery if they could make him an Arran Oloroso Cask matured whisky. Arran Distillery denied because of the low availability of Oloroso Sherry Casks. So the owner bought a fresh Oloroso cask by himself and let fill in 400 litre of spirit by the Arran Distillery (they even ask him from where he got this cask). On contrary to the text on the bottle the whisky was fully matured in a 1st fill Oloroso cask, not just finished. After 15 years of maturing the distillery wanted to buy the casks but this time the Lochranza hotel owner denied. Due to trade mark reason the bottling is not named after the Arran Distillery but Arran Distilleries water source the Easan Biorach (Ease-N Beer-akh). According to the owner this bottling should be the only Oloroso matured Arran whisky. I have no idea why it is stated "finished" and not "matured".
Before I forget it: The whisky is really something coming pretty close to a Macallan CS. For me great whisky with a nice Scottish story behind it.