Harcourt was elected as MP for Lichfield in 1806 and which he represented until he was elected for Oxfordshire in 1831. By 1850 he had become the longest-serving member, and so became the Father of the House of Commons for the last 11 years of his life.
On 27 March 1815, he married Lady Elizabeth Bingham (the eldest daughter of the 2nd Earl of Lucan) and they had one child, Elizabeth Lavinia (d. 1858, married Montagu Bertie, 6th Earl of Abingdon). Harcourt's wife died in 1838 and he then married Frances Waldegrave (the widow of the 7th Earl Waldegrave and future wife of the 1st Baron Carlingford), a daughter of the noted tenor, John Braham.
- Stooks Smith, Henry. (1973) [1844-1850]. Craig, F. W. S. (ed.). The Parliaments of England (2nd ed.). Chichester: Parliamentary Research Services. pp. 258–259, 298. ISBN 0-900178-13-2.
- Craig, F. W. S. (1989) . British parliamentary election results 1832–1885 (2nd ed.). Chichester: Parliamentary Research Services. p. 442. ISBN 0-900178-26-4.
- Record for George Granville Vernon-Harcourt on thepeerage.com
- G. E. Cokayne; with Vicary Gibbs, H.A. Doubleday, Geoffrey H. White, Duncan Warrand and Lord Howard de Walden, editors. The Complete Peerage of England, Scotland, Ireland, Great Britain and the United Kingdom, Extant, Extinct or Dormant, new ed., 13 volumes in 14 (1910-1959; reprint in 6 volumes, Gloucester, U.K.: Alan Sutton Publishing, 2000), volume I, page 49.
- L. G. Pine. The New Extinct Peerage 1884-1971: Containing Extinct, Abeyant, Dormant and Suspended Peerages With Genealogies and Arms (London, U.K.: Heraldry Today, 1972), page 54.
- Hansard 1803–2005: contributions in Parliament by George Harcourt
|Parliament of the United Kingdom|
Sir George Anson
Sir John Wrottesley
| Member of Parliament for Lichfield
With: Sir George Anson
Sir George Anson
Sir Edward Scott
| Member of Parliament for Oxfordshire
With: Richard Weyland 1831–1837
Lord Norreys 1832–1852
Hon. Thomas Parker 1837–1841
Joseph Warner Henley 1841–1862
John North 1852–1862
John William Fane
Joseph Warner Henley
John Sidney North
| Father of the House
Sir Charles Burrell