During the Second World War, Tristan was commissioned by the Royal Navy as the stone frigate and used as a secret signals intelligence station to monitor Nazi U-boats (which were required to maintain radio contact) and shipping movements in the South Atlantic Ocean. This weather and radio station led to extensive new infrastructure being built on the island, including a school, a hospital, and a cash-based general store. The first colonial official sent to rule the island was Sir Hugh Elliott in the rank of Administrator (because the settlement was too small to merit a Governor) 1950–53. Development continued as the island's first canning factory expanded paid employment in 1949. Prince Philip, Duke of Edinburgh, the Queen's consort, visited the islands in 1957 as part of a world tour on board the royal yacht HMY "Britannia".