1721 in Great Britain

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Events from the year 1721 in Great Britain.

Incumbents

Monarch – George I
Prime Minister – Robert Walpole (Whig) (starting 3 April){{cite web |title=The National Archives - Sir Robert Walpole: Britain’s first Prime Minister |url=https://blog.nationalarchives.gov.uk/sir-robert-walpole-britains-first-prime-minister/ |website=The National Archives blog |access-date=12 June 2023 |date=1 April 2021}}

6 January – The Committee of Inquiry on the collapse of the South Sea Company publishes its findings.
5 February – Lord Stanhope, chief minister, dies a day after collapsing while vigorously defending his government's conduct over the "South Sea Bubble" in Parliament.
9 March – John Aislabie imprisoned in the Tower of London, found guilty of corruption for his part in the collapse of the South Sea Company as Chancellor of the Exchequer.{{cite book|last=Williams|first=Hywel|title=Cassell's Chronology of World History|url=https://archive.org/details/cassellschronolo0000will|url-access=registration|location=London|publisher=Weidenfeld & Nicolson|year=2005|isbn=0-304-35730-8}}
c. March – Atterbury Plot to restore the Stuart monarchy begins.
4 April – Robert Walpole becomes the first Prime Minister (although this is more a term of disparagement at this time).{{cite web|title=Sir Robert Walpole|url=http://www.number10.gov.uk/history-and-tour/sir-robert-walpole/|work=10|publisher=HM Government|accessdate=2011-11-16|archive-url=https://web.archive.org/web/20111101195959/http://www.number10.gov.uk/history-and-tour/sir-robert-walpole/|archive-date=2011-11-01|url-status=dead}}

Lady Mary Wortley Montagu introduces smallpox inoculation to Britain: the Princess of Wales is persuaded to test the treatment and the procedure becomes fashionable.
Thomas Guy founds Guy's Hospital in London.{{cite web|url=http://www.gsttcharity.org.uk/aboutus/index.html|title=History of Guy's and St Thomas' Charity|accessdate=2007-09-03|archiveurl=https://web.archive.org/web/20070928081956/http://www.gsttcharity.org.uk/aboutus/index.html|archivedate=28 September 2007}}
Regular mail service between London and New England is established.{{cite book|author1=Clear, Todd R.|author2=Cole, George F.|author3=Resig, Michael D.|year=2006|title=American Corrections|edition=7th|publisher=Thompson}}

Nathan Bailey publishes An Universal Etymological English Dictionary.
Thomas Parnell's A Night-Piece on Death is published, inaugurating the "Graveyard poets" movement.

2 January – John Manners, Marquess of Granby (died 1770)
19 March – Tobias Smollett, physician and author (died 1771)
15 April – Prince William Augustus, Duke of Cumberland, military leader (died 1765)
14 July – John Douglas, Anglican bishop and man of letters (died 1807)
4 August – Granville Leveson-Gower, 1st Marquess of Stafford, politician (died 1803)
31 August – George Hervey, 2nd Earl of Bristol, statesman (died 1775)
9 November – Mark Akenside, poet and physician (died 1770)
6 December – James Elphinston, philologist (died 1809)

27 January – Joshua Churchill, politician
5 February – James Stanhope, 1st Earl Stanhope, statesman and soldier (born c. 1673)
16 February – James Craggs the Younger, politician (born 1686)
24 February – John Sheffield, 1st Duke of Buckingham and Normanby, statesman and poet (born 1648)
16 March – James Craggs the Elder, politician (born 1657)
April – Mary Read, pirate, in Jamaica
11 June – Sir Anthony Deane, naval architect and politician (born 1633)
8 July – Elihu Yale, East India merchant and educationist (born 1649 in Massachusetts)
3 August – Grinling Gibbons, sculptor (born 1648 in Rotterdam)
18 September – Matthew Prior, poet and diplomat (born 1664)
11 October – Edward Colston, merchant and philanthropist (born 1636)
13 December – Alexander Selkirk, sailor (born 1676 in Scotland)
17 December – Richard Lumley, 1st Earl of Scarbrough, statesman (born 1650)