HMS Taurean

The HMS Taurean was a Royal Navy Trafalgar Class submarine, which, after hacking into the UNIT computer systems, Mickey Smith discovered was situated ten miles off the coast of Plymouth. It carried a Sub-Harpoon UGM-84A missile, which the Ninth Doctor then used to destroy 10 Downing Street and the family Slitheen members still inside. (DW: World War Three)