The Dean of Christ Church Cathedral, Dublin is the senior official of that church, the cathedral of the United Diocese of Dublin and Glendalough in the Church of Ireland, and head of the Chapter, its governing body. A Dean has presided over Christ Church Cathedral since around 1539, before which the cathedral was a Priory under Augustinian rules, headed by a Prior, back to the time of Archbishop St. Laurence O'Toole. Aspects of the cathedral administration are overseen by the Cathedral Board, which the Dean chairs (with both a regular and a casting vote).