A Timeline of UK Time: From Greenwich in 1675 to Today
UK time has been shaped by astronomers, railways, wars and Acts of Parliament. This timeline puts the key dates in order.
Greenwich and railway time
1675: King Charles II founds the Royal Observatory at Greenwich to help sailors find their longitude.
1840: The Great Western Railway adopts London time along its line, and other railways follow.
1880: Greenwich Mean Time becomes the legal time across Great Britain.
1884: The International Meridian Conference in Washington chooses Greenwich as the prime meridian.
1924: The BBC first broadcasts the Greenwich Time Signal, the pips.
Summer time and the wars
1916: Summer time is introduced during the First World War to save fuel.
1941 to 1945 and 1947: British Double Summer Time, two hours ahead of GMT, is used in summer.
1968 to 1971: The British Standard Time trial keeps the UK on GMT+1 all year.
1972: The Summer Time Act sets modern rules for British Summer Time.
The modern era
1996: The UK and the EU harmonise on the last Sunday of October for the end of summer time, creating the present rule.
Today: the clocks go forward at 01:00 GMT on the last Sunday of March and back at 02:00 BST on the last Sunday of October, and the National Physical Laboratory keeps UK time with atomic clocks.
Frequently asked questions
When did the UK start summer time?
In 1916, during the First World War, to save fuel by making better use of daylight.
Clock change guides
- What Is Daylight Saving Time (DST)? A Plain-English GuideWhat daylight saving time is, how it works in the UK, Europe and the US, why it exists, its history, who uses it and the argument over scrapping it.
- Why Do the Clocks Go Back in October? The Real ReasonThe clocks go back in autumn to return the UK to GMT, so winter mornings are lighter. The history, the rule, what time it happens and what changes for you.
- When Do the Clocks Go Forward Again After Going Back?When the UK clocks go forward again after the autumn change, how long the UK stays on GMT, when evenings get lighter and how to remember to reset your clocks.