William Johnstone was the son of Thomas and Margaret Johnstone of Milford, Auckland.

He died when his ship, HMS Neptune, hit several mines in the sea off Tripoli and sank in December 1941.

132 New Zealand ratings went missing as a result of the loss of H.M.S. Neptune. HMS Neptune was launched at Portsmouth on 31 January 1933. She was one of five 'Leander' class light cruisers completed between 1933 and 1935. Two others were HMS Achilles and Leander serving in the RNZN. They displaced 7,200 tons, could make 32 knots and carried eight 6 inch guns and 550 crew. The Neptune was in the Mediterranean from 1 December 1941 as part of Force K which was searching for Axis shipping, especially those taking supplies to Rommel in North Africa. Early on the 19th the ships of Force K ran into a minefield.The Neptune hit three or four mines and sank with only one survivor. At the same time the Aurora was badly damaged and Penelope slightly.Trying to reach Neptune to assist, the destroyer Kandahar was mined and had to be scuttled the following day. On the same day in Alexandria harbour the Queen Elizabeth with Admiral Cunningham on board and the Valiant were both badly damaged and sank.The Mediterranean Fleet battle squadron ceased to exist. Of the total crew of 766 there was only one survivor.He was rescued off a raft five days later by an Italian destroyer and spent the rest of the war in a prisoner of war camp. AWMM