The King William Banks buoy is situated about 12 miles east of the northern tip of the Isle of Man. It marks the eastern extremity of the bank of this name and is an important turning point, especially for the British Railway ships on the Heysham to Belfast run. This buoy, which is unlit, is a third class spherical buoy and thus presents a poor radar target. The British Railway ships are fitted with radar and always pass the buoy at night so that if it could be detected by radar regularly it would be of great assistance to navigation. In fact complaints were made about its radar reflecting properties, and accordingly a pentagonal cluster of 12 in. corner reflectors designed by the Admiralty Signal and Radar Establishment was supplied to Trinity House and mounted on the buoy on 3 March 1949 (see Notice to Mariners 619/49) at a height of 11 ft. 6 in. above the water.