Last Hammerhead Down South -  one of the most evocative and distinctive signs of the British Empire is the cantilever cranes, largely with the great Scottish engineering firm of Sir William Arrol, Glasgow, was once the symbol of British Maritime Power across the globe.   In Sydney at Garden Island one of these massive cranes is under threat of removal, being now more ornament than use,    The crane has not been in use since 1996 and yet incurs running costs amounting to some A$ 770,000 per year to keep it safe.    The crane was constructed at the end of the Second World War and its primary use was to load the giant guns onto the largest of British battleships. Today the crane remains as the largest dockside crane in Australia.   The Hammerhead of the Clyde was removed in 2007,