The history of British Summer Time
From a builder’s 1907 pamphlet to wartime fuel-saving and a three-year national experiment, here is how the UK came to change its clocks twice a year.
| Year | What happened |
|---|---|
| 1907 | Builder William Willett publishes The Waste of Daylight, arguing for lighter evenings. |
| 1915 | Willett dies, aged 58, before his idea becomes law. |
| 1916 | The Summer Time Act 1916 receives Royal Assent on 17 May; clocks first go forward on 21 May 1916, to save fuel in the First World War. |
| 1941–1945 | British Double Summer Time: clocks two hours ahead of GMT in summer and one hour ahead in winter, to save energy in the Second World War. |
| 1947 | Double Summer Time briefly returns during the post-war fuel crisis. |
| 1968–1971 | The British Standard Time experiment keeps clocks one hour ahead of GMT all year round. It is abandoned after a Commons vote. |
| 1972 | The Summer Time Act 1972 restores the seasonal change and sets the modern framework. |
| 2002 | The Summer Time Order 2002 fixes the current last-Sunday dates in line with EU harmonisation. |
How did British Summer Time begin?
Direct answer. British Summer Time began with the Summer Time Act 1916, which moved UK clocks forward an hour in summer to save fuel during the First World War. The clocks first changed on 21 May 1916.
The idea had been championed years earlier by William Willett, a builder from Kent who published The Waste of Daylight in 1907 after noticing how many people slept through summer mornings. Willett lobbied Parliament for years but died in 1915, before the measure was adopted — Germany introduced a similar scheme weeks before Britain in 1916.
Key fact: The Summer Time Act 1916 introduced BST; clocks first went forward on 21 May 1916.
What was Double Summer Time?
Direct answer. During the Second World War the UK used British Double Summer Time: clocks two hours ahead of GMT in summer and one hour ahead even in winter, to maximise daylight and save energy.
Double Summer Time ran each summer from 1941 to 1945 and was used again briefly in 1947 during a severe post-war fuel crisis. Outside those summers the winter clocks stayed one hour ahead of GMT, so for several years Britain never returned to plain GMT at all.
Key fact: In WWII summers (1941–45) UK clocks were two hours ahead of GMT under Double Summer Time.
Why did the 1968–1971 experiment fail?
Direct answer. From 1968 to 1971 Britain kept clocks one hour ahead of GMT all year — British Standard Time — to test permanent lighter evenings. Parliament voted to end it in 1971.
Evening road casualties fell, but winter mornings stayed dark much later, especially in Scotland and northern England where the sun would not rise until well after 09:00. Concern for children travelling to school and early-start workers led the House of Commons to scrap the experiment in a free vote. That north–south tension still shapes the debate today.
Key fact: The 1968–71 British Standard Time experiment was abandoned mainly over dangerously dark winter mornings in Scotland and the north.
FAQ
Who invented British Summer Time?
The idea in Britain is credited to William Willett, a London builder who published a pamphlet called The Waste of Daylight in 1907. He campaigned for it until his death in 1915, a year before it became law.
When did British Summer Time start?
BST was first introduced by the Summer Time Act 1916. The clocks first went forward on 21 May 1916, partly to save coal and fuel during the First World War.
Did Britain ever stop changing the clocks?
Yes — from 1968 to 1971 Britain ran an experiment called British Standard Time, keeping clocks one hour ahead of GMT all year. It was dropped after concerns about dark winter mornings, especially in Scotland and the north.
Sources & further reading
We cite primary and authoritative sources. Time-zone rules can change when governments amend the law — always confirm critical timing with an official source.