7 January – The BBC Forces Programme begins broadcasting; it becomes the most popular channel among civilians at home as well as its primary target audience.
8 January – Food rationing introduced;[2] it will remain in force until 1954.
9 January – World War II: liner Dunbar Castle of the Union Castle Line hits a mine in the English Channel and sinks with the loss of 9 men (2 dead and 7 missing).
17 January – A wave of freezing weather afflicting most of Europe leads to the River Thames freezing for the first time since 1888.
16 March – First civilian casualty of bombing in the UK, on Orkney.[5]
18 March – Last terrorist bomb in the Irish Republican Army's S-Plan campaign on the British mainland (and until 1973) explodes harmlessly on a London rubbish dump.[6]
23 April – The War Budget sees the introduction of Purchase Tax and an increase in tobacco duties.
2 May – Last British and French troops evacuated from Norway following failure in the Norwegian Campaign.[8]
7–9 May – Norway Debate in the House of Commons. Strong opposition to the Chamberlain ministry's conduct of the war make it impossible for him to continue as Prime Minister.
9 May
In private discussions, Viscount Halifax rules himself out as successor to Chamberlain in favour of Winston Churchill.[9]
Neville Chamberlain resigns as Prime Minister, and is replaced by Winston Churchill with a coalition war ministry.[2]
British Invasion of Iceland, following the German invasion of Denmark and Norway, to avert a possible German occupation of the island, in violation of Iceland's neutrality.
5 June – Novelist J. B. Priestley broadcasts his first Sunday evening radio Postscript, "An Excursion to Hell", on the BBC Home Service, marking the role of the pleasure steamers in the Dunkirk evacuation.
17 June – RMSLancastria, serving as a troopship, is bombed and sunk by the Luftwaffe while evacuating British troops and nationals from Saint-Nazaire with the loss of at least 4,000 lives, the largest single UK loss in any World War II event, immediate news of which is suppressed in the British press.[14] Destroyer HMSBeagle(H30) rescues around 600.
18 June
Churchill makes his Battle of Britain speech to the House of Commons: "...the Battle of France is over. The Battle of Britain is about to begin... if the British Empire and its Commonwealth last for a thousand years, men will still say, This was their finest hour." He repeats the speech on BBC radio this evening.
Operation Catapult aims to take French navy ships into British control or destroy them to prevent them falling into German hands. Those in port at Plymouth and Portsmouth are boarded and in an attack on Mers-el-Kébir British naval units sink or seize ships of the French fleet anchored in the Algerian ports of Mers El Kébir and Oran. The following day, Vichy France breaks off diplomatic relations with Britain.
Adolf Hitler makes a peace appeal ("appeal to reason") to Britain in an address to the Reichstag. BBC German-language broadcaster Sefton Delmer unofficially rejects it at once[23] and Lord Halifax, British foreign minister, flatly rejects peace terms in a broadcast reply on 22 July.
13 August – Adlertag ("Eagle Day") strike on southern England occurs, starting the rapid escalation of the Battle of Britain.
18 August
"The Hardest Day" in the Battle of Britain: both sides lose more aircraft combined on this day than at any other point during the campaign without the Luftwaffe achieving dominance over the RAF.
31 August – Texel Disaster: Two Royal Navy destroyers are sunk by running into a minefield off the coast of the occupied Netherlands with the loss of around 400 men, 300 of them dead.[27]
2 September – Destroyers for Bases Agreement between the United Kingdom and United States is announced, to the effect that 50 U.S. destroyers needed for escort work will be transferred to Britain. In return, the United States gains 99-year leases on British bases in the North Atlantic, West Indies and Bermuda.[28]
4 September – Adolf Hitler's Winterhilfe speech at the Berlin Sportpalast declares that Nazi Germany will make retaliatory night air raids on British cities and threatens invasion.[28]
7 September
The Blitz begins with "Black Saturday". This will be the first of 57 consecutive nights of strategic bombing on London.[2]
British high command issues the code "Cromwell" to troops, alerting them to possible German invasion.[19]
10 September – A bomb at South Hallsville School, Canning Town in the East End of London kills at least 77 and perhaps four times as many.[29]
11 September – Churchill, speaking from the Cabinet War Rooms, warns of a possible German invasion.[28]
23 September – King George VI announces the creation of the George Cross decoration during a radio broadcast.[2]
27 September – Battle of Graveney Marsh in Kent, the last exchange of shots with a foreign force on mainland British soil, takes place when soldiers of the London Irish Rifles capture the crew of a downed new German Junkers Ju 88 bomber who initially resist arrest with gunfire; one of the enemy is shot in the foot.[34][35]
14–15 November – Coventry Blitz: the centre of Coventry is destroyed by 500 German Luftwaffe bombers: 150,000 incendiary devices, 503 tons of high explosives and 130 parachute mines level 60,000 of the city's 75,000 buildings. At least 568 people are killed, while 863 more are injured.[2] Exceptionally, the location and nature of the damage here is immediately publicised in the media.
19 November – Less than a week after the blitz of Coventry, further heavy air raids take place in central England. Birmingham,[38]West Bromwich,[39]Dudley and Tipton[40] are all bombed. Some 900 people are killed and 2,000 more injured – there are 53 deaths at the Birmingham Small Arms Company factory in Small Heath alone. Most of the region's casualties are in Birmingham.
12–15 December – Sheffield Blitz ("Operation Crucible"): the city of Sheffield is heavily bombed by the Luftwaffe. 660 people are killed, while another 1,500 are injured and 30,000 more left homeless.
20 December – An anti-aircraft shell fired from Dudley accidentally strikes a public house in neighbouring Tipton, resulting in dozens of casualties.
20–21 December – Liverpool Blitz: Liverpool is heavily bombed, with well over 300 people killed and hundreds more injured.
22 December – Manchester Blitz: Manchester is heavily bombed as the Luftwaffe air raids on Britain continue. 363 are killed and 1,183 wounded; and Manchester Cathedral is badly damaged.
Old Age and Widows' Pensions Act reduces the pensionable age for insured women and the wives of pensioned men from 65 to 60.[44]
Following the outbreak of World War II, housebuilding is halted, but some 1.1 million council houses have been built in the last 20 years to replace slum property, although the need for further demolition and rehousing remains, including the issue of rehousing families left homeless by air raids.[45]
Draper, Alfred (1979). Operation Fish: The Fight to Save the Gold of Britain, France and Norway from the Nazis. Don Mills: General Publishing. ISBN9780773600683.
"Red Cross Gift Shop". Worthing Gazette. 17 July 1940. p.4. The Worthing Division of the British Red Cross Society is opening a Red Cross Gift Shop in Chapel-road, Worthing for a month from to-morrow...