The Chief Secretary for Ireland was a key office-holder of state in the British administration in Ireland. He was in theory #2 in Dublin Castle, an aide to the #1 Lord Lieutenant (= Viceroy). However, from the late 18c., the office frequently eclipsed the Lord Lieutenant's. The Chief Secretary managed the legislative business for the Government in the Irish House of Commons, in which he sat as an M.P. He operated in a manner similar to that of the Prime Minister in the British Parliament.

This CDV shows Spencer Cavendish, Marquess of Hartington, who was Chief Secretary for Ireland 1871 - 1874. His brother Lord Frederick Cavendish held briefly the position in 1882 and was assassinated during the Phoenix Park Murders.