Events from the year 1870 in the United Kingdom.
- 28 January – General Post Office takes over business of private telegraph companies.
- 5 March – first ever (unofficial) international football match, England v Scotland, takes place under the approval of the Football Association at The Oval, London.
- 10 May – Jem Mace wins the boxing championship of the world, defeating fellow Englishman Tom Allen at Kenner, near New Orleans.
- 19 May – the Home Government Association is established in Ireland by Isaac Butt to argue for devolution for Ireland and repeal of the Act of Union 1800.
- late Spring – Army Enlistment (Short Service) Act allows reduction in length of enlistment to the British Army as part of the Cardwell Reforms.
- 2 June – competitive examination for entry to the British civil service introduced.
- 23 June – Keble College, Oxford, opens, the first new college of the University of Oxford in more than a century.
- 2 August – official opening of the Tower Subway beneath the River Thames in London, the world's first underground passenger "tube" railway. Although this lasts as a railway operation only until November, it demonstrates the technologically successful first use of the cylindrical wrought iron tunnelling shield devised by Peter W. Barlow and James Henry Greathead.
- 4 August – British Red Cross established as the British National Society for Aid to the Sick and Wounded in War by Lord Wantage.
- 9 August
- 1 October – postcards and halfpenny postage stamps introduced by the Post Office.
- Undated – the David Greig grocery chain begins with a store in London.
- ^ Blake, Richard. The Book of Postal Dates, 1635–1985. Caterham: Marden. p. 15.
- ^ Mace, Ralph. "Jem Mace, Champion of the World". Retrieved 2010-08-09.
- ^ a b Williams, Hywel (2005). Cassell's Chronology of World History. London: Weidenfeld & Nicolson. pp. 422–423. ISBN 0-304-35730-8.
- ^ Ensor, R.C.K. (1936). 14, "England 1870–1914". The Oxford History of England. Oxford University Press. p. 16.
- ^ a b Palmer, Alan; Palmer, Veronica (1992). The Chronology of British History. London: Century Ltd. pp. 291–292. ISBN 0-7126-5616-2.
- ^ a b c d Penguin Pocket On This Day. Penguin Reference Library. 2006. ISBN 0-14-102715-0.
- ^ Smith, Denis (2001). Civil Engineering Heritage: London and the Thames Valley. Thomas Telford. pp. 22–23. ISBN 0-7277-2876-8.
- ^ Cox, Michael, ed. (2004). The Concise Oxford Chronology of English Literature. Oxford University Press. ISBN 0-19-860634-6.