His half-brother Robert had made a brilliant diplomatic and political career. Charles and his half-brother remained lifelong friends and wrote each other many letters. Robert helped Charles to start a diplomatic career.
Berlin From May 1813 until the end of the war, Sir Charles was Envoy Extraordinary and
Minister Plenipotentiary to Berlin, and was also Military Commissioner with the allied armies, being wounded at the
Battle of Kulm in August 1813.
Vienna In 1814 he was also appointed Ambassador to Austria, a post he held for nine years (1814–1823). On 18 June 1814, to make him more acceptable in Vienna, Stewart was ennobled as
Baron Stewart, of Stewart's Court and Ballylawn in
County Donegal, by the Prince Regent. In the same year, he received
honorary degrees from
Oxford and
Cambridge, was admitted to the
Privy Council, and was appointed a
Lord of the Bedchamber to the
king. Lord Stewart, as he now was, attended the
Congress of Vienna with his half-brother Lord Castlereagh as one of the British plenipotentiaries. He was not well regarded as he made a spectacle of himself with his loutish behaviour, was apparently rather often inebriated, and frequented prostitutes quite openly. He earned himself the sobriquet of Lord
Pumpernickel after a loutish character in a play in fashion. In the following years he also served as British observer at the congresses of
Troppau,
Laibach and
Verona. As the great powers were taking an increasingly reactionary approach, the British government sent Lord Stewart to observe, but not participate in the decisions.
Second marriage and children '' by
Thomas Lawrence, 1818 Before the end of his diplomatic career Lord Stewart had, on 3 April 1819, married his second wife,
Lady Frances Vane-Tempest, a daughter and heiress of
Sir Henry Vane-Tempest, at her mother's house in
Bruton Street,
Mayfair, and took her surname of
Vane, by Royal licence, as had been stipulated in her father's will. He was henceforth known as Charles William Vane, whereas his son from his first marriage stayed Frederick Stewart. Children by Lady Frances Vane-Tempest: •
George Henry Robert Charles William Vane-Tempest, 5th Marquess of Londonderry (1821–1884) •
Lady Frances Anne Emily Vane (1822–1899); married
John Spencer-Churchill, 7th Duke of Marlborough. •
Lady Alexandrina Octavia Maria Vane (1823–1874), godchild of Alexander I of Russia; married
Henry Dawson-Damer, 3rd Earl of Portarlington. •
Lord Adolphus Frederick Charles William Vane-Tempest (1825–1864), politician; became insane, and had to be medically restrained. • Lady Adelaide Emelina Caroline Vane (c. 1830–1882); disgraced the family by eloping with her brother's tutor, Rev. Frederick Henry Law. • Lord Ernest McDonnell Vane-Tempest (1836–1885), fell in with a
press-gang and had to be bought a commission in the army, from which he was subsequently
cashiered. Through his daughter Lady Frances, Lord Londonderry is the maternal grandfather of
Lord Randolph Churchill, and consequently a great-grandfather of
Winston Churchill.
Castlereagh's suicide '' by
Thomas Lawrence. Stewart was shocked by his elder brother's suicide in 1822 and resigned his post as Ambassador to Austria after the
Congress of Verona. On 12 August 1822, his half-brother committed suicide. He succeeded his half-brother as
3rd Marquess of Londonderry in 1822. The following year Lord Londonderry was also created
Earl Vane and
Viscount Seaham, of
Seaham in the County Palatine of Durham, with remainder to the heirs male of the body of his second wife. His half-brother's death also meant the end of his diplomatic career. He quit the diplomatic service in 1823.
Queen Victoria had a low opinion of Londonderry's abilities as a civil servant. She said that he should, in her opinion, not be given any post of importance.
Residences Lord Londonderry used his new bride's immense wealth to acquire the
Seaham Hall estate in
County Durham, developing the coalfields there. He also built the harbour at Seaham, to rival nearby
Sunderland. He commissioned
Benjamin Wyatt to build a mansion at
Wynyard Park. It was completed by
Philip Wyatt in 1841 and cost £130,000 (equivalent to £10,772,000 in 2016) to build and furnish. Unfortunately, just as the mansion was being completed, a fire broke out and gutted the house; it was later restored and remodelled by
Ignatius Bonomi. The family also used their newfound wealth to redecorate their country seat in Ireland,
Mount Stewart, and bought Holdernesse House on London's
Park Lane, which they renamed
Londonderry House. == Declines Orange invitation ==