William was born in Wolverhampton on 17 February 1878. He was the son of William and Sarah Mason, living at 58 Johnson Street, Dudley Road, Wolverhampton.
He was an established electrical fitter working as an Admiralty Civilian for HM Dockyard in Devonport. He was serving on board the HMS Inflexible, which was involved in various battles, including at Dardanelles. On 18 March 1915 the ship was trying to suppress Turkish guns so that minefields could be swept. Unfortunately, the return fire was heavy, with a number of shells hitting the ship, killing or wounding many on board. One of the men who died was William Mason. He was buried at sea, and is commemorated on the Plymouth Naval Memorial. The value of his effects was £114 9s. 9d.