This is Thorn Island, another of the forts in the Stack Rock chain but this has been used as a hotel up until about 15 years ago. In 2011 it was put up for sale and, just to tempt you there was planning permission for a cable car to connect it to the mainland. I'm not sure if it was ever sold so if you are interested click this link for the usual estate agents blurb, (including a boast!). Quite interesting photos though.