|Covid-19|Monarch - George III
Prime Minister - William Pitt the Younger (Tory)
20 January - London Docks open.
21 February - Charles Manners-Sutton confirmed as Archbishop of Canterbury.
18 April - Ordnance Survey begins systematic publication its General Survey of England and Wales ("Old Series") maps to a scale of one inch to the mile (1:63,360) with those for Essex.
4 June - The first Trooping the Colour ceremony at the Horse Guards Parade in London.
3 August - The annual cricket match between Eton College and Harrow School is played for the first time.
21 October - Napoleonic Wars: Battle of Trafalgar - British naval fleet led by Admiral Horatio Nelson defeats a combined French and Spanish fleet off the coast of Spain. Admiral Nelson is fatally shot.
6 November - News of the victory at Trafalgar and Nelson's death reaches London.
26 November - The Ellesmere Canal's Pontcysyllte Aqueduct is opened in Wales, the tallest and longest in Britain.
Anglo-Spanish War, 1796–1808
Napoleonic Wars, 1803–1815
John Dalton's paper "On the Absorption of Gases by Water and Other Liquids". Memoirs of the Literary and Philosophical Society of Manchester, 2nd series 1: pp. 271–87, including the first published list of relative atomic masses.
Walter Scott's narrative poem The Lay of the Last Minstrel.
First printed version of the folk song "Bobby Shafto's Gone to Sea" in its modern (Tyneside) version.
27 January - Samuel Palmer, artist (died 1881)
8 March - Rayner Stephens, Scottish-born radical reformer and Methodist minister (died 1879)
20 March - Thomas Cooper, Chartist, poet and religious lecturer (died 1892)
5 July - Robert FitzRoy, admiral and meteorologist (suicide 1865)
29 August - Frederick Maurice, theologian (died 1872)
22 December - John Obadiah Westwood, entomologist (died 1893)
2 January - Alexander Wedderburn, 1st Earl of Rosslyn, Lord Chancellor (born 1733)
3 January - Charles Towneley, antiquary (born 1737)
30 January - John Robison, physicist (born 1739)
18 January - John Moore, Archbishop of Canterbury (born 1730)
2 February - Thomas Banks, sculptor (born 1735)
William Buchan, doctor (born 1729)
Thomas Pownall, colonial statesman (born 1722)
7 May - William Petty, 2nd Earl of Shelburne, Prime Minister (born 1737)
25 May - William Paley, philosopher (born 1743)
3 August - Christopher Anstey, writer (born 1724)
28 August - Alexander Carlyle, church leader (born 1722)
5 October - Charles Cornwallis, 1st Marquess Cornwallis, general (born 1738)
21 October - Horatio Nelson, admiral (mortally wounded in battle) (born 1758)
1805 in the United Kingdom Wikipedia
Events from the year 1805 in the United Kingdom of Great Britain and Ireland. This is the year of the Battle of Trafalgar.