He was born William Robert to
Maurice Edward Dockrell and
Margaret Dockrell on 22 October 1886 in Dublin, Ireland but he was later baptised George Shannon Dockrell. He came from a prominent political family in Dublin. Sir Maurice Edward Dockrell was a Unionist Politician and was one of the few members who took his seat in the British House of Commons after the
1918 general election. His mother, Lady Margaret Dockrell (née Shannon) was a suffragette, who actively campaigned for women's rights, and was a member of Dublin City Council. They were married in 1875 and eventually both his parents worked in the family business of Thomas Dockrell, Sons and Co. Ltd. His family was raised Protestant, within the Church of Ireland. Dockrell spent his school years, from 1899 to 1903 in Trent College, Nottingham where he excelled at swimming. He received his education at
Trinity College Dublin. Several of Dockrell's siblings went to work alongside their parents at Thomas Dockrell, Sons and Co. Ltd. Meanwhile, Dockrell became more actively involved in his own swimming career. His niece,
Marguerite Dockrell, and nephew,
Hayes Dockrell, also went on to compete in the 1928 Summer Olympics in Amsterdam. Like Dockrell, his niece competed in swimming, while his nephew took part in the water polo section. ==Swimming career==