The son of the distinguished British historian James Grant Duff, he was educated at Grange School and Balliol College, Oxford, before being called to the English bar.

He practised and taught law for a short time before starting a political life and entering the House of Commons as the Liberal Member of Parliament for Elgin Burghs.

Duff was born in Eden, Banff, Banffshire on 21 February 1829, the elder son of James Grant Duff, a well-known Indian official from Bombay Presidency and British Resident in the princely state of Satara, and his wife Jane Catherine, daughter of Sir Whitelaw Ainslie.

He studied law at the Inns of Court and passed with honours, ranked only behind James Fitzjames Stephen.

[2] He was called to the bar at Inner Temple, London on 17 November 1854[3] and practised as a junior under William (later Mr Justice) Field.

In 1868, William Ewart Gladstone appointed Duff Under-Secretary of State for India under the Duke of Argyll.

When Gladstone came back to power in 1880, Grant Duff was appointed Under-Secretary of State for the Colonies and sworn of the Privy Council.

From old Sicilian recollections, I gave in 1884 to our new creation the name of Marina; and I was not a little amused when walking there last winter with the Italian General Saletta, he suddenly said to me 'On se dirai a Palerme'.

Mr Grant-Duff, how you stand like an extinct volcano in the midst of the ruins of your abortive reputation as an administrator!

He came out as Governor of Madras with great expectations, and we find him feeble, sickly, unable to do his work himself, and wholly in the hands of the permanent officials.

Though a clever man, he had spent all his life in the confined atmosphere of the House of Commons, and was quite unable to deal with a state of society so strange to him as that which he found in India[7]The Madras Mahajana Sabha was established in 1884 with P. Rangaiah Naidu as its president and R. Balaji Rao as its vice-president.

The Indian National Congress held its first session at Bombay in December 1885, attended by 72 delegates including 22 from the Madras Presidency.

[2] He was Chairman of the Liberty and Property Defence League, established to curb socialist tendencies in the Liberal Party.

In April 1859 he married Anna Julia Webster; they had four sons and four daughters, including: He died in his home in Chelsea, London in January 1906, aged 76,[18] and was buried in Elgin Cathedral, Scotland.