Mystery Island

This is Thorn Island, off West Angle Bay at the entrance to Milford Haven in Pembrokeshire
The fort was built on the two-acre island in 1854 to guard the entrance to Milford Haven against the threat of invasion by Napoleon.
It was converted into a hotel in 1947 and was sold in 1999 for £275,000 to the Von Essen hotel group who intended spending four million pounds to reopen the hotel with a five star rating and a cable car to allow access from the mainland.
But in April 2011 it was put on the market with a price tag of £750,000 along with 26 hotels in the UK and one in France, following the collapse of Von Essen, with debts of more than £250m.
The island was finally sold in November 2011 for 'significantly less' than the guide price to Kent Mushrooms who are the owner of historical locations including Chislehurst Caves in Kent. They say they plan to explore the 'possibilities of future commercial use of the island'.

Nothing further is known :-)