Londesborough was the eldest son of Albert Denison, 1st Baron Londesborough, and Henrietta Mary Weld-Forester. Henry Conyngham, 1st Marquess Conyngham, was his paternal grandfather. He was elected to the House of Commons for Beverley in 1857, a seat he held until 1859, and then represented Scarborough from 1859 to 1860, when he succeeded his father in the barony and entered the House of Lords. In 1887 he was created Viscount Raincliffe, of Raincliffe in the North Riding of the County of York, and Earl of Londesborough, in the County of York.

Lord Londesborough married Lady Edith Frances Wilhelmina Somerset, daughter of Henry Somerset, 7th Duke of Beaufort, in 1863. He died in April 1900, aged 65, and was succeeded in his titles by his son William. Lady Londesborough died in 1915.

References

• Kidd, Charles, Williamson, David (editors). Debrett's Peerage and Baronetage (1990 edition). New York: St Martin's Press, 1990.
• Leigh Rayment's Peerage Page
• www.thepeerage.com