St Catherine’s Island, Tenby, Pembrokeshire

© David Clapp/Alam

The beach fort of Tenby

Rising out of the sea in Tenby, St Catherine’s Island is formed from a limestone outcrop about 25m (82ft) high, on the Pembrokeshire coast. Our homepage image shows the scene at low tide, when the island can be reached by foot across Castle Beach. Riddled with small caves, for centuries this tiny island was home only to a small chapel dedicated to St Catherine and, reportedly, some sure-footed sheep. But fears of a naval invasion from France, under its first president Emperor Napoleon III, saw plans drawn up for a series of forts along this stretch of the Welsh coast in the late 1850s.

In the end, no attack was forthcoming and St Catherine’s fort, built between 1867 and 1870, never saw action. Some felt the Victorian fort had been a big waste of money as, by the time it was built, the threat from the French navy had subsided. It was sold into private hands in 1907 and became a lavish home before going back into military service during the Second World War. It was sold off again in the 1960s and housed a zoo for just over a decade until 1979. Since then, it’s largely been left empty, although more recently it has opened to the public for tours. Fans of TV’s Sherlock may also recognise it as the location of the maximum security prison in the final episode of its fourth series.