According to his naval record, William Reid was born in Belfast on 14 December 1885 although his birth certificate records a date of birth a year earlier on 14 December 1884.  Details of his family are unknown, but his mother is given as Mrs E Reid, of Carnsore Coastguard Station in a Belfast Telegraph notice of 1916.

William Reid joined the Royal Navy as a Boy 2nd Class in May 1901 at HMS BLACK PRINCE, the Training Ship at Queenstown (now Cobh), County Cork. He gave his previous occupation as ‘mill worker’. After further training and harbour service he joined HMS SIRIUS on the China Station in March 1903 where he was rated Ordinary Seaman on his 18th birthday, and Able Seaman in May 1905. In 1906, he attended HMS DEFIANCE, the Devonport Torpedo School and qualified as a Torpedoman. Over the next eight years he served in the pre-dreadnought battleship HMS VENGEANCE, the cruiser HMS FORTH, and at Gibraltar in HMS CORMORANT where he was probably embarked in destroyers.  In February 1914 he signed on to complete 22 years. After four months with the Coastguard Signal Station at Carnsore, County Wexford, he was drafted in August 1914 to the submarine depot ships HMS DOLPHIN and then HMS MAIDSTONE.  It seems likely that he joined HMS E7 in Spring of 1915 and then sailed with her to the Mediterranean in June 1915, in company with E2 and E12, coming on to the books of the Mediterranean submarine depot ship, HMS ADAMANT, on 10 June 1915.

HMS E7 completed one highly successful patrol in the Sea of Marmara during June/July 1915 for which her CO, Lt Cdr Archibald Cochrane was awarded the DSO, and several crew members earned DSMs. Whilst attempting to re-enter the Dardanelles on her next patrol, E7 became entangled in newly-laid anti-submarine nets off Nagara Point. On 4 September 1915, after many hours attempting to work free, Turkish/German attacks forced her to the surface where her crew were all taken prisoner and E7 was scuttled to avoid capture. 

William Reid died at the Red Cross Hospital, Angora (Ankara, Turkey) on 12 February 1916, and was one of four E7 prisoners of war who died in captivity.  He is buried at Baghdad (North Gate) War Cemetery.