Mr James Bertram Williamson was born at Phibsboro Avenue in Dublin, Ireland on 28 November 1876.

He was the son of David Wallace Williamson (b. 1840), an engine driver, and Eleanor Grace Webster (b. 1844). Both his parents were Presbyterians from Edinburgh and they had married in their home city on 17 July 1863 before going on to have eleven recorded children. 

The couple had initially settled in Old Monkland, Coatbridge, Lanarkshire and are listed there on the 1871 Scottish census with their son John who was the fifth of their children. Their first, a stillborn daughter arrived on 17 May 1864 followed by a stillborn son on 27 February 1865 and another stillborn son on 13 November 1865. Son David Munro arrived on 15 September 1867 but died shortly after. He would be followed by John Webster (b. 29 June 1869) and Emily (b. 25 June 1871), the latter dying in early infancy.

The family crossed the Irish Sea and settled in Dublin where six more children were born: Eleanor Grace (b. 9 July 1872), Georgina Callan (b. 9 August 1874), Agnes Maude (b. 15 March 1881), Christine Mary (b. 13 March 1884) and Flora (b. 6 September 1886).

In Dublin his father continued to work as an engine driver and his elder brother John a compositor; John died 4 November 1895 aged 26. His father later died from tuberculosis on 2 February 1899. Around 1894 young James had begun his career with the Post Office.

When James appears on the 1901 census of Ireland he is described as a sorter at the General Post Office and he is living with his widowed mother and siblings at 2 Downham Villas in Arran Quay, Dublin.

Williamson would be absent from the following census in 1911 when his family were living at 11 Lindsay Terrace, Bontanic Road in Glasnevin, Dublin and he may have been at sea, having obtained a transfer to Southampton a while previously where he was reportedly courting a girl named Gladys Copeland whose father operated the Queensland Hotel in Southampton1. Whilst the identity of this woman is unclear, a Gladys Annie Copeland (b. 1895 in Southampton) was listed on the 1911 census as the daughter of licensed victualler Charles Copeland and his wife Sarah Louisa, recorded at that time as living at 76 Clovelly Road, Southampton, the same street that James was reported to have lived in 1912. What became of Gladys Copeland is unknown but she may have resettled in the USA.

James was reported to have lived at 93 Clovelly Road, Southampton. He worked on Titanic as one of five postal clerks. Several accounts by survivors describe these men dragging sackloads of mail from the already waterlogged sorting rooms to higher decks. All five men were lost in the sinking. James' body, if recovered, was never identified.

He is remembered by a memorial plaque in the Abbey Presbyterian Church, Parnell Square, Dublin:

To the Glory of God and in memory of
James B. Williamson
Of the Transatlantic Post Office
Who died on duty in the foundering
of the SS 'Titanic' April 15th 1912
By this tablet the members of
the Postal and Telegraph Services
Record their Deep Sorrow at his death

His mother Eleanor died from cardiac failure in hospital on 6 July 1913; she was still a resident of Botanic Road at the time. His last known surviving sibling, Flora, died in Dublin in 1977 (as Mrs Charles Landers).