George Henry Robert Charles William Vane-Tempest, 5th Marquess of Londonderry, KP (26 April 1821 – 6 November 1884), styled Viscount Seaham between 1823 and 1854 and known as The Earl Vane between 1854 and 1872, was a British aristocrat, businessman, diplomat and Conservative politician.
Born George Vane, he was the second son of Charles Vane, 1st Baron Stewart, but his eldest son by his second wife, the former Frances Vane-Tempest, daughter and heiress of Sir Henry Vane-Tempest, 2nd Baronet. His father, born Charles Stewart, was the second surviving son of Robert Stewart, 1st Marquess of Londonderry, and had changed his surname in 1819 on marrying his second wife. The eldest surviving son of the 1st Marquess, and therefore George Vane's uncle, was the statesman Robert Stewart, Viscount Castlereagh, who had succeeded as 2nd Marquess only 20 days before George's birth.
The 2nd Marquess died the next year, and George's father succeeded as 3rd Marquess; George thereby became Lord George Vane. His half-brother (by his father's first wife, and therefore not affected by the surname change), Frederick Stewart, became Viscount Castlereagh by courtesy; he later succeeded as 4th Marquess.
In 1823, the 3rd Marquess was created Earl Vane and Viscount Seaham, with remainder to his sons by his second wife. As the eldest of those sons, Vane became heir apparent to those peerages, and became Viscount Seaham by courtesy.
Lord Seaham was educated at Eton and Balliol College, Oxford.
Viscount Seaham entered the 1st Life Guards, purchasing a lieutenancy on 7 February 1845, and retiring on 5 May 1848. He was returned to parliament for Durham North in 1847, a seat he held until 1854.
That year he succeeded his father as Earl Vane and entered the House of Lords. In 1867 he was sent on a special mission as Envoy Extraordinary to Russia to Emperor Alexander II, to invest the emperor with the Order of the Garter.
When his half-brother, Frederick Stewart, 4th Marquess of Londonderry, died childless in 1872, Earl Vane inherited the marquessate and family estates. Two years later George Vane-Tempest, 5th Marquess, was appointed a Knight of the Order of St Patrick. In 1880 he became Lord-Lieutenant of County Durham, a post he held until his death four years later.
He was appointed Lieutenant-Colonel Commandant of the 2nd (Seaham) Durham Artillery Volunteer Corps on 26 March 1864. This was a part-time unit largely recruited from his family's Seaham Colliery, and his younger brother and later two of his sons also became officers in the unit. The Marquess of Londonderry was succeeded in the command in 1876 by his eldest son.
See the 5th Marquis of Londonderry