Marquess of Lansdowne is a title in the Peerage of Great Britain created in 1784, and held by the head of the Petty-Fitzmaurice family.

[4] In 1753, the earldom held by his uncle was revived when he was made Earl of Shelburne, in the County of Wexford, in the Peerage of Ireland.

From 1765 until the Reform Act 1832, the head of the family controlled the two seats in parliament of the pocket borough of Calne in Wiltshire.

He was succeeded by his son from his first marriage to Lady Sophia Carteret, John Henry Petty-Fitzmaurice, 2nd Marquess of Lansdowne.

He died childless in 1809 and was succeeded by his half-brother, the third Marquess, the son of their father’s second marriage, to Lady Louisa FitzPatrick.

In a ministerial career spanning over fifty years, he served as Chancellor of the Exchequer from 1806 to 1807, as Home Secretary from 1827 to 1828, as Lord President of the Council from 1830 to 1834, 1835 to 1841, and 1846 to 1852, and as Minister without Portfolio from 1852 to 1858.

His eldest son, Henry Petty-Fitzmaurice, sat as Unionist Member of Parliament for West Derbyshire from 1908 to 1918 and was a Senator of the Irish Free State in 1922.

On his death in 1936 he was succeeded by his second but eldest surviving son, the seventh Marquess, who was killed in action in 1944 during the Second World War, unmarried.

Born George John Charles Mercer Nairne, he assumed by Decree of the Lord Lyon the additional surnames of Petty-Fitzmaurice in 1947.