Educated in England at Reading grammar school under Richard Valpy, he graduated at Trinity College Dublin, in 1825, and was called to the Irish Bar in 1830.
[1] In 1864 Prendergast was appointed by Lord Romilly a commissioner, with Charles William Russell, for selecting official papers relating to Ireland for transcription from the Carte manuscripts in the Bodleian Library.
[1] Prendergast issued for private circulation The Tory War in Ulster ...Descriptive of Ireland from the Restoration to the Revolution, A.D. 1660-1690[2] (1868, Dublin, 2 pts.).
In politics he was a liberal, contributed to the old Nation newspaper, and replied there in 1872–4 to James Anthony Froude's lectures in America on Irish history.
[1] Prendergast married, on 1 September 1838, Caroline, second daughter of the radical political pamphleteer and freethinker George Ensor of Ardress House, County Armagh, and left one son, Francis, who settled in California and became a naturalised American.