[2][3] Peacocke was born at St Mary's Rectory, Dublin,[4] son of Rt.
Revd Joseph Irvine Peacocke, bishop of Derry and Raphoe 1916–1945.
He was ordained deacon in 1926 and was curate of Seapatrick (Dromore) in the period 1926–1930.
On 16 October, he was appointed by the electoral college as Bishop of Derry and Raphoe and enthroned in St Columb's Cathedral on 22 January 1970.
[8] Peacocke was elected Bishop of Derry and Raphoe on 16 October 1969 and consecrated 6 January 1970.