It's also 100 years since the date on which we put the clocks back was switched from the third Saturday in September to the first Saturday in October. That's not how things work any more, indeed the rules for putting clocks forward and back have changed many times over many years. So I thought I'd try to summarise all the changes since British Summer Time was first introduced. It's a complicated tale that thankfully gets simpler as the years go forward. [dates & times] [dates] [legislation]
As an initial indication of how complicated it is, here's a quick summary of the month in which the clocks changed.
| Year | Clocks forward | Clocks back |
| 1916 | May | October |
| 1917-1924 | March or April | September or October |
| 1925-WW2 | April | September |
| WW2 | Double Summer Time | |
| WW2-1960 | April | October |
| 1961-1967 | March | October |
| 1968-1971 | Permanent Summer Time | |
| 1972-2025 | March | October |
We should probably start at the beginning.
1907: William Willett, a builder from Chislehurst, publishes a pamphlet proposing that clocks be advanced in April and put back in September. This would increase evening daylight and reduce expenditure on lighting.
1908: The Daylight Saving Bill is introduced in Parliament. It is voted down by 124 votes to 91. Winston Churchill is in favour.
1916: Germany introduces daylight saving to support the war effort. Three weeks later the UK follows suit, passing the Summer Time Act. ("the prescribed period shall be from two o'clock in the morning Greenwich mean time on Sunday the twenty-first day of May until two o'clock in the morning Greenwich mean time on Sunday the first day of October")
1917-1922: Summer time continues, the dates decided each year by an Order in Council.
| Year | Clocks forward | Clocks back |
| 1916 | Sunday 21 May | Monday 1 October |
| 1917 | Sunday 8 April | Monday 17 September |
| 1918 | Sunday 24 March | Monday 30 September |
| 1919 | Sunday 30 March | Monday 29 September |
| 1920 | Sunday 28 March | Monday 25 October* |
| 1921 | Sunday 3 April | Monday 3 October |
| 1922 | Sunday 26 March | Sunday 8 October** |
** In 1922 the morning for turning the clocks back switched from Monday to Sunday, and it's been Sunday ever since.
In summer 1922, a new Summer Time Act was passed. This set the start date as "the day next following the third Saturday in April, or, if that day is Easter Day, the day next following the second Saturday in April" and the end date as "the day next following the third Saturday in September". Like so.
| Year | Clocks forward | Clocks back |
| 1923 | Sunday 22 April | Sunday 16 September |
| 1924 | Sunday 13 April* | Sunday 21 September |
1922's Summer Time Act was made permanent in 1925 so that Parliament didn't need to renew it each year. The 1925 Act also changed the end date to "the day after the first Saturday in October". This made things a lot simpler.
| Years | Clocks forward | Clocks back |
| 1925-1938 | the day after the second Saturday in April (unless this is Easter Day* in which case one week earlier) | the day after the first Saturday in October |
In 1939 war against Germany triggered another change, this time to make best use of daylight and reduce the length of the evening blackout.
The Defence (Summer Time) Regulations...
i) delayed the end of Summer Time in 1939 by seven weeks
ii) introduced permanent Summer Time in 1940
iii) introduced Double Summer Time from 1941 onwards.
Clocks did not go back in autumn 1940 but did go forward in spring 1941, putting the country on GMT+2 for the first time. GMT was not observed between February 1940 and October 1945, Britain was either on Summer Time or Double Summer Time.
| Year | Clocks forward | Clocks back | |
| 1939 | Sunday 16 April | GMT+1 | Sunday 19 November* |
| 1940 | Sunday 25 February | GMT+1 | - |
| 1941 | Sunday 4 May | GMT+2 | Monday 10 August |
| 1942 | Sunday 5 April | GMT+2 | Monday 9 August |
| 1943 | Sunday 4 April | GMT+2 | Monday 15 August |
| 1944 | Sunday 2 April | GMT+2 | Monday 17 September |
Extricating ourselves from Double Summer Time proved complicated. In 1945 the clocks had to go back twice, once in July and once in October. Double Summer Time was then reintroduced as an emergency measure in 1947 because of severe fuel shortages resulting from the harsh winter. 1947 is the only year the clocks changed four times.
| Year | Clocks forward | Clocks back | |
| 1945 | Monday 2 April* | GMT+2 | Sunday 15 July AND Sunday 7 October |
| 1946 | Sunday 14 April | GMT+1 | Sunday 6 October |
| 1947 | Sunday 16 March AND Sunday 13 April | GMT+2 | Sunday 10 August AND Sunday 2 November |
| 1948 | Sunday 14 March | GMT+1 | Sunday 31 October |
| 1949 | Sunday 3 April | GMT+1 | Sunday 30 October |
In the 1950s there was no longer a need to extend summer time to support industry and fuel companies. The dates thus reverted to those introduced in 1925 - partially in 1950 and fully in 1953.
| Years | Clocks forward | Clocks back |
| 1950-1952 | the day after the second Saturday in April (unless this is Easter Day* in which case one week earlier) | the day after the third Saturday in October |
| 1953-1960 | the day after the first Saturday in October |
** 1960 was the last year the clocks went forward in April.
In 1960 the government consulted 178 organisations as part of an inquiry into the future of Summer Time. A slight majority preferred keeping Summer Time all year round but this was not adopted. Instead the statutory period of Summer Time was extended by three weeks in both spring and autumn (then in 1964 extended again by a week in the spring).
| Years | Clocks forward | Clocks back |
| 1961-1963 | the last Sunday in March | the day after the third Saturday in October |
| 1964-1967 | the day after the fourth Saturday in March |
After a further inquiry in 1967 the new Labour government decided to introduce British Standard Time, a three year trial in which Britain would remain on GMT+1 throughout the year. The clocks did not go back at the end of October 1968, thus effectively adopting Central European Time. In December 1970 the new Conservative government held a debate on the continuation of British Standard Time. MPs decided to end the experiment by a vote of 366 to 81.
| Year | Clocks forward | Clocks back | |
| 1968 | Sunday 18 February | GMT+1 | - |
| 1969 | - | GMT+1 | - |
| 1970 | - | GMT+1 | - |
| 1971 | - | GMT+1 | Sunday 31 October |
After the experiment everything returned to the previous pattern for the rest of the decade.
Then in 1980 the European Union introduced their first harmonisation directive. This...
i) mandated a common start date across the EU (the last Sunday in March)
ii) permitted the UK & Ireland a separate finish date to the rest of the EU (who changed at the end of September)
iii) harmonised the time the clocks changed (now 1am GMT, not 2am GMT)
| Years | Clocks forward | Clocks back |
| 1972-1980 | the day after the fourth Saturday in March (at 2am GMT) | the last Sunday in October (at 2am GMT) |
| 1981-1995 | the last Sunday in March (at 1am GMT) | the last Sunday in October (at 1am GMT) |
In 1994 the EU's seventh directive on summer-time arrangements fixed a common end date across the EU from 1995 onwards. In the opposite of what you might expect, they forced all the other EU countries to adopt the same end date as the UK, i.e. the last Sunday in October. To ease in the new arrangements, 1995's date was brought ahead by a week as a one-off.
| Years | Clocks forward | Clocks back |
| 1995 | the last Sunday in March | Sunday 22 October |
| 1996-2025 | the last Sunday in March | the last Sunday in October |
And so it is that for the last 30 years our clocks have gone forward on the last Sunday in March and back on the last Sunday in October, no faff, no twiddles.
Since we left the EU in 2020 it's been possible for Britain to make its own decisions on summer time but nobody's dared risk it. Any changes would lead to time zone differences on the island of Ireland, plus it's always been a hugely divisive issue with no solutions that suit everyone so the status quo looks likely to continue. You may not like how and when we put the clocks forward and back, but at least "the last Sunday of the month" keeps it simple.