William was born in Whitstable, Kent, and was the son of Henry William Clothier. According to the 1891 Census when he was 4, William's father was a master mariner, his mother was Clara Clothier 38, he had an older sister Clara Clothier 8 and a younger brother Alfred Jas Clothier 2. They lived at 144 Kitchenham Place, Whitstable.
He attended Armstrong College, and studied botany, English, Latin, Greek, ancient history, French and history. According to the 1911 Census he was an elementary schoolmaster for Northumberland County age 24, lodging/boarding with a widow and her 2 young children (Mrs. Alice Louie Holmboe) at 18 Warkworth Avenue Whitley Bay. He went on to become a Headmaster at Presbyterian School, Belford, Northumberland. He married Annie May Clothier who previously lived at Nesham House, Ponteland, Newcastle-upon-Tyne. They lived at West Street, Belford.
At the outbreak of war, William enlisted in Alnwck, Northumberland. William attained the rank of Bombardier in the Royal Garrison Artillery 352nd Siege Battery. William was killed in action on 24th July 1917 aged 31.