Sir Thomas Newenham Deane, Irish architect, is born in Dundanion, County Cork on June 15, 1828. He is the son of Sir Thomas Deane and Eliza Newenham, and the father of Sir Thomas Manly Deane. His father and son are also architects.

Deane is educated at Trinity College, Dublin, from 1845 to 1849. On January 29, 1850, he marries Henrietta Manly, daughter of Joseph H. Manly of Ferney, County Cork. He and his wife have several children.

Deane joins his father’s architecture practice in 1850 and, in 1851, he becomes a partner along with Benjamin Woodward. Their work is primarily a Gothic style influenced by the principles of John Ruskin, and include the museum at Trinity College, Dublin, the Oxford University Museum of Natural History, the Pitt Rivers Museum, the Kildare Street Club in Dublin, and Queen’s College Cork, now University College Cork. He is known as a conservation architect, involved in the restoration, including the incorporation of the original twelfth-century Romanesque chancel, of St. Mary’s Cathedral, Tuam.

Deane’s work on the conservation of St. Canice’s Cathedral, Kilkenny, is less successful and brings him into conflict with the dean and chapter, and in particular with the treasurer James Graves. It is possibly his interest in the restoration of medieval buildings which leads to his appointment as the first Inspector of National Monuments under the Irish Board of Works after the disestablishment of the Church of Ireland brought ruined buildings under their care. His work includes St. Cronan’s Church, Roscrea, County Tipperary.

In contemporary circles, Deane’s partner Woodward is seen as the creative influence behind the business, and their practice suffers after his early death on May 15, 1861. Nevertheless, Deane continues to work with his son, Thomas Manly Deane, designing the National Museum of Ireland and National Library of Ireland in Kildare Street, Dublin. He is knighted in 1890.

On November 8, 1899, Deane dies suddenly in his office on St. Stephen’s Green, into which he had only just moved. He is buried in Deans Grange Cemetery, where his son Thomas designs and erects a cross in his memory.