The dominant position of the Lord Lieutenant at Dublin Castle had been central to the British administration of the Kingdom of Ireland for much of its history.[5] Over time, the post of Chief Secretary gradually increased in importance, particularly because of his role as manager of legislative business for the Government in the Irish House of Commons, in which he sat as an MP.Chief Secretary Viscount Castlereagh played a key role in the enactment of the Act of Union which passed in the Irish Parliament on its second attempt in 1800 through the exercise of patronage and direct bribery.However, the existing system of administration in Ireland continued broadly in place, with the offices of Lord Lieutenant and Chief Secretary retaining their respective roles.The last Chief Secretary to represent an Irish constituency while in office was Chichester Parkinson-Fortescue, MP for County Louth, who served from 1868 to 1871.
Chief Sectretary's Lodge, Phoenix Park, now the Deerfield Residence of the U.S. Ambassador