Mr William John Gregg was born in Belfast, Ireland on 11 March 1869. Hailing from a Church of Ireland family, he was the son of William Gregg, a slater, and Ellen Devlin. 

He was married in St Patrick’s Church, Ballymacarrett, Belfast on 13 September 1895 to Jane George (b. 1875), the daughter of a mariner. By 1911 they had eight children.

The 1901 census shows William and his family residing at 19 Gertrude Street, east Belfast and he is described as a ship’s fireman. By 1911 the family address was 3 Fox Street. 

Gregg’s ship prior to Titanic had been the Black Head. He joined Titanic at Belfast for the delivery trip to Southampton where he then disembarked.

William and his wife Jane had welcomed a daughter named Margaret in September 1913. Jane’s health took a downturn soon after and she died in a Belfast sanitorium on 10 November 1913. William died on 18 July 1923 and he is buried in Dundonald Cemetery (plot B2 664).