Background
He was the son of Captain Honorary Windham Henry Wyndham-Quin (1829-1865), a younger son of Windham Quin, 2nd Earl of Dunraven and Mount-Earl, by his wife Caroline Tyler, daughter of Rear-Admiral Sir George Tyler.
Member of Parliament in the United Kingdom
He was the son of Captain Honorary Windham Henry Wyndham-Quin (1829-1865), a younger son of Windham Quin, 2nd Earl of Dunraven and Mount-Earl, by his wife Caroline Tyler, daughter of Rear-Admiral Sir George Tyler.
He succeeded to the Earldom on the death of his kinsman Windham Wyndham-Quin, 4th Earl of Dunraven and Mount-Earl, who died in 1926 without male issue. Wyndham-Quin was a Major in the 16th Lancers, and served in the First Boer War in 1881. He again volunteered for service in South Africa in 1900, during the Second Boer War, and was appointed a captain in the Imperial Yeomanry on 14 February 1900.
He raised and commanded the Glamorgan Imperial Yeomanry contingent, which served as a company in the 1st battalion Imperial Yeomanry, and on 18 April 1900 he was appointed 2nd in command of this battalion.
He was promoted to the honorary rank of Colonel 19 October 1901. He was re-elected in 1900, but lost the seat in the 1906 general election.
He served as High Sheriff of County Kilkenny for 1914. They had the following children:
Richard Southwell Windham Robert Wyndham-Quin, 6th Earl of Dunraven and Mount-Earl (1887–1965)
Captain Honorary
Valentine Maurice Wyndham-Quin (22 May 1890 – 1983), married Marjorie Pretyman in 1919 and had three daughters, including Marjorie Olein, wife of Robert Gascoyne-Cecil, 6th Marquess of Salisbury, and Pamela, wife of John Wyndham, 6th Baron Leconfield
Lady Olein Wyndham-Quin (5 March 1892 – 1969)
Mission Kathleen Sybil Wyndham-Quin (1895–1907).
26th United Kingdom Parliament. 27th United Kingdom Parliament]
In the 1895 general election he was elected Member of Parliament for South Glamorganshire, winning the seat for the Conservative Party.