William Harold Welch was born in Southampton, Hampshire, England on 15 December 1890. He was the son of Charles William Welch (b. 1864) and his wife Mary Jane (b. 1866) who were from Weymouth, Dorset and Southampton respectively, had married around 1888. They would have two children, Charles Leslie (b. 1896) and William.

William first appears on the 1891 census as a 4-month-old living at 54 Radcliffe Road, St Mary, Southampton. His father is described as a Grocer's shop keeper. The family are living at Antelope Buildings, St Mary's Road, Southampton by the time of the 1901 census. On the 1911 census William is absent but his parents and brother are resident at Allandale, St Catherines Road, Bitterne Park, Southampton.

When he signed-on to the Titanic, on 4 April 1912, he gave his address as Northern Bond Road, Bitterne Park, Southampton. His last ship had been the Edinburgh Castle. As an assistant cook he received monthly wages of £4 10s.

William Welch, who was unmarried, died in the sinking. His body, if recovered, was never identified.

William's parents continued to live in Southampton. His mother passed away in 1931 followed by his father in 1948.