29 January – George IV of the United Kingdom ascends the throne on the death at Windsor Castle of his father George III (after 59 years on the throne), ending the period known as the Regency era which began in 1811. George IV has served as prince regent during this time due to his father's mental deterioration.[2] The title Prince of Wales falls into abeyance for 21 years.
1–2 April – A Proclamation, signed "By order of the Committee of Organisation for forming a Provisional Government", is distributed in the Glasgow area, beginning the "Radical War" in Scotland. The following day, around 60,000 – particularly weavers – stop work across a wide area of central Scotland. Disaffection spreads to the West Riding of Yorkshire.
5 April – Radical War: Troops capture radicals at Bonnybridge.[6]
8 April – Radical War: Radical prisoners from Paisley are freed from jail in Greenock after militia have killed eight of the crowd.[6]
Robert Owen's Report to the County of Lanark, of a plan for relieving public distress and removing discontent (published 1821) is delivered in Scotland as the beginning of a plan to devise the labour voucher.
5 June – Caroline of Brunswick, the new King's estranged wife, returns to England after six years abroad in Italy, where she has been carrying on an affair, and attracts the support of radical mobs. Since ascending the throne, the King has sought to receive his government's approval for a divorce.[9][10]
5 July – Pains and Penalties Bill put before Parliament to deprive Caroline of Brunswick, George IV's estranged wife, of the title of Queen Consort, leading to her de facto public trial before the House of Lords opening on 17 August. Although narrowly passed on 10 November in the House of Lords, the bill is withdrawn in the knowledge that it would almost certainly not pass the House of Commons.[10]