CLIFF divers completed a daring plunge 18 metres into the Thames Estuary from the Maunsell Forts.

British divers Gary Hunt, who is reigning world champion, and Blake Aldridge, a 2008 Olympian, took part in a group dive.

They were practising on Sunday for the Red Bull Cliff Diving World Series in Wales on Saturday.

Blake said: “I’m looking forward to Wales as it will be the first time the Red Bull Cliff Diving World Series has come to the UK.

“Competing in front of a home crowd is going to be very special, and, of course, I’ll be doing my new dive, which is the world’s hardest dive.”

The forts, which include the Principality of Sealand, are ten miles off the coast of Southend.

They were built in the Second World War to help defend the UK. Having been decommissioned in the Fifties, they were re-occupied for pirate radio, including Radio Caroline, in the mid-Sixties, until they were closed in 1967.