He was born in Wimborne, Dorset, England in 1859, later being baptised on November 13th of that same year.
He was the son of William Humphreys (b. 1834), a publican, and his wife Elizabeth (b. 1837), both natives of Wimborne. He had one known sibling, Rosa Alice (b. 1858).
At the time of Sidney's birth his father was a licensed victualler but by the time of the 1861 census the family had relocated to Southampton where his father now worked as a ship's steward, the family living at 54 French Street. The family whereabouts over the next few decades are unclear but it is believed that they remained in Southampton.
Sidney was married in Southampton in 1895 to Annie Rosetta Snoad (b. 1874), a native of Sittingbourne, Kent, and the couple had six children: William F. (1894 - 1945), Sidney Herbert (b. 1897), Horace John (1899-1959), Leslie Graham (1900 - 1928), Hetty Grace (1902 - 1971, later Mrs Richard Sheils) and Arthur (b. 1904).
The family are shown on the 1901 census living at 7 Pound Street and the 1911 census living at 40 Redcar Street, both in Shirley, and on both occasions Sidney being described as a seaman. By 1912 the family were listed on the Southampton Street directory living at 113 Duke's Road.
When Humphreys signed on to the Titanic on April 10th, 1912; he gave his address as 113 Duke's Road, Southampton and his previous ship as the Olympic. Serving as quartermaster he could expect monthly wages of £5.
On the night of the sinking Humphreys recalled the three bellboys (Arthur Barratt, Clifford Henry Harris and William Albert Watson) being corralled to their regular posts so as not to get in the way and observed them smoking and joking with passengers. Humphreys was placed in charge of lifeboat 11 and survived the sinking.
Sidney Humphreys returned to England and presumably continued working at sea. He remained living in Southampton and passed away in 1919 aged 60. His widow Annie died in 1936.
His son William settled in New York with his wife, the former Dorothy Baker (b. 1900), and had two children: Ronald (b. 1919) and Joyce (b. 1920). He worked as a labourer in Queens but was widowed in 1930. William died in Manhattan on November 22nd 1945 aged 51 and was buried in Flushing Cemetery, New York.