The son of the John Thornton Leslie-Melville, 9th Earl of Leven and his second wife, Sophia, daughter of Henry Thornton MP, he was educated at Windlesham House School and Eton College.

He was a Director of the Peninsular and Oriental Steam Navigation Company and of the Bank of England.

He was a Scottish representative peer from 1892 until his death, Keeper of the Privy Seal of Scotland from 1900 until his death, and Lord High Commissioner to the General Assembly of the Church of Scotland for nine successive years 1898–1906.

He was appointed a Privy Counsellor in the 1902 Coronation Honours list,[5] and was sworn a member of the council at Buckingham Palace on 11 August 1902.

He was a close friend of the Maharajah Duleep Singh and accompanied him on a voyage from England to Italy which began in December 1856.