Sam moved to London when he got a job in the British Civil Service. He joined and captained the successful London Hibernians Gaelic football team. G.A.A. records state that in 1900, 1901 and1903 he captained the London Hibernians to All Ireland Finals.
In 1907 Sam went into the administration of the London G.A.A. becoming the chairman and a delegate to the GAA's Annual Congress.
A strange coincidence is that the Vice Chairman of the London County Board was Liam McCarthy, who has the All Ireland Senior Hurling Championship Cup called after him.
Sam Maguire joined the Irish Republican Brotherhood in 1909 and rose to the rank of Lieutenant-General along with Director of Intelligence in Britain.
Sam Maguire fled to Dublin in December 1923 and he got a job in the newly established Irish Civil Service. However because of his political opinions and his sympathies to the Anti-Treaty forces, he clashed with his superiors and was dismissed.