1840 in the United Kingdom

Incumbents

• Monarch – Victoria
• Prime Minister – William Lamb, 2nd Viscount Melbourne
• Parliament – 13th

  Events

• 1 January – trial of Welsh Chartists John Frost, Zephaniah Williams and William Jones for their part in the Newport Rising of 1839 opens at Monmouth before Chief Justice Tindal. This is the first trial where proceedings are recorded in shorthand.
• 10 January – Uniform Penny Post introduced, replacing the Uniform Fourpenny Post of 1839.
• 12 January – Chartist rising in Sheffield aborted.
• 14 January – Chartist rising in the East End of London largely suppressed by police.
• 16 January – Frost, Williams and Jones are all found guilty of high treason for their part in the Chartist riots, and are sentenced to death; the last time the sentence of hanging, drawing and quartering is passed in the U.K., although following a nationwide petitioning campaign and, extraordinarily, direct lobbying of the Home Secretary by the Lord Chief Justice, it is commuted to transportation for life.
• 22 January – British colonists reach New Zealand. Official founding date of Wellington.
• 26 January – Chartist rising in Bradford fails to spread.
• 6 February – Treaty of Waitangi, a document granting British sovereignty in New Zealand, is signed.
• 10 February – Queen Victoria marries her cousin Prince Albert of Saxe-Coburg and Gotha in the Royal Chapel at St James's Palace.
• 15 April – King's College Hospital opens in Portugal Street, London.
• 27 April – the foundation stone of the new Palace of Westminster is laid as its reconstruction following the Burning of Parliament in 1834 begins.
• 1 May – issue of the Penny Black, the world's first postage stamp, together with Mulready stationery. The stamp becomes valid for prepayment of postage from 6 May.
• 5 May - Thomas Carlyle gives the first lecture in the series On Heroes, Hero Worship and the Heroic in History
• 11 May – Chartist leader Feargus O'Connor is sentenced to imprisonment in York Castle for seditious libel over speeches published in The Northern Star.
• 20 May – York Minster's nave roof is destroyed in an accidental fire.
• 6 June – the first group of British emigrants from The Church of Jesus Christ of Latter-day Saints set sail from Liverpool bound for Nauvoo, Illinois.
• 10 June – Edward Oxford fires a pistol at Queen Victoria in Hyde Park, London.
• 12–23 June – the World Anti-Slavery Convention is organised by the British and Foreign Anti-Slavery Society at Exeter Hall in London.
• July
• * Fresh water is piped to Buxton Market Place by the 6th Duke of Devonshire, beginning the Buxton well dressing festival.
• * Last known great auk in the British Isles caught and later killed on the islet of Stac an Armin, St Kilda, Scotland.
• 4 July – the Cunard Line's 700-ton wooden paddle steamer departs from Liverpool bound for Halifax, Nova Scotia, on the first steam transatlantic passenger mail service.
• 15 July – Austria, Britain, Prussia, and Russia sign the London Treaty with the Sublime Porte, ruler of the Ottoman Empire.
• 23 July – the Province of Canada is created by the Act of Union.
• 7 August – Chimney Sweepers and Chimneys Regulation Act 1840 prohibits the employment of children under the age of 21 as chimney sweeps.
• 10 September – Ottoman and British troops bombard Beirut and land troops on the coast to pressure Egyptian Muhammad Ali to retreat from the country.
• 16 September – Joseph Strutt hands over the deeds and papers concerning the Derby Arboretum, which is to become England's first public park.
• 30 September – foundation of Nelson's Column laid in London, Trafalgar Square being laid out and paved during the year.
• 11 October – Maronite leader Bashir Shihab II surrenders to the Ottomans and on 14 October goes into exile, initially in Malta.
• 10 November – the boiler of an experimental steam locomotive named Surprise explodes near Bromsgrove station in Worcestershire, killing the driver, Thomas Scaife, and fireman, Joseph Rutherford.
• 8 December – David Livingstone leaves for Africa.
• 21 December – Stockport Viaduct is completed. It is one of the largest brick structures in Europe.

  Undated

• The Royal Society for the Prevention of Cruelty to Animals gains its Royal status.

  Ongoing events

• First Opium War
• First Anglo-Afghan War

  Publications

• W. Harrison Ainsworth's novels Guy Fawkes and The Tower of London.
• Charles Dickens' novel The Old Curiosity Shop.
• "Thomas Ingoldsby"'s The Ingoldsby Legends.
• Agnes Strickland's Lives of the Queens of England begins publication.
• William Makepeace Thackeray's novel Catherine.
• William Whewell's book The Philosophy of the Inductive Sciences, founded upon their history, in which he introduces the words "Physicist" and "Scientist".

  Births

• 1 January – Dugald Drummond, railway engineer
• 18 January – Henry Austin Dobson, poet and essayist
• 26 January – John Clayton Adams, landscape painter
• 5 February – John Boyd Dunlop, inventor
• 29 February – John Philip Holland, inventor
• 31 March – Benjamin Baker, civil engineer
• 27 April – Edward Whymper, mountaineer
• 2 June – Thomas Hardy, novelist and poet
• 20 June – George Selwyn Marryat, fly fisherman
• 21 June – Edward Stanley Gibbons, philatelic stamp dealer
• 9 October – Simeon Solomon, painter
• 21 November – Victoria, Princess Royal
• 29 November – Rhoda Broughton, writer

  Deaths

• 6 January – Fanny Burney, novelist
• 18 February – Jeffry Wyattville, architect and garden designer
• 30 March – Beau Brummell, arbiter of fashion
• 1 May – Joseph Williamson, philanthropist and builder of Williamson's tunnels
• 26 May – Sidney Smith, admiral
• 28 July – John George Lambton, 1st Earl of Durham
• 22 September
• * Princess Augusta Sophia of the United Kingdom
• * Anne Lister, landowner, diarist, mountaineer and traveller, "the first modern lesbian"