Britain has made a second in respect of Ascension island in the South Atlantic, a third concerning the Hatton-Rockall area in the North Atlantic and a fourth concerning the Falklands, South Georgia and the South Sandwich islands in the South Atlantic.

ECONOMIST: The scramble for the seabed

The commanding officer said one of the most memorable parts of the deployment was the journey down to South Georgia and the South Sandwich Islands, which he described as "some of the most unique and beautiful places on earth".

BBC: HMS Montrose returns after south Atlantic deployment