Perched on a tiny outcrop of rock at the edge of the Atlantic, 'the Bishop' has something special about it for the Trinity House officers who man Britain's light-houses. It's the last lighthouse for westward-bound ships, and the last still operating almost as it did under Queen Victoria's patronage. Tony Parker talks with the men who still maintain their lonely vigil in the ' Ships' Graveyard,' off the Isles of Scilly.