Daylight Saving Time UK: When do the clocks change and why do we change them?

When do the clocks change in spring and autumn and why do we change them? Our guide looks briefly at the history of daylight saving in the UK, plus when it happens in 2021.

Alarm clock in nature/

Here is our guide to daylight saving in the UK, looking at when and why the clocks change, plus don’t forget to change your clocks this weekend!


Why do we change the clocks?

The policy was first introduced on 17th May 1916 in an attempt to save fuel, namely candles and coal, during World War One. Daylight Saving Time (DST) became permanent when parliament passed the Summer Time Act, which became known as British Summer Time (BST).

The campaign to use BST was first started in 1907 by a British builder called William Willett from Kent who wanted the country to make the most of the daylight hours in the summer months and save vital fuel. He wrote the pamphlet ‘The Waste of Daylight’ arguing the case for daylight saving time. Willett at first wanted the clocks to be changed by 20 minutes every Sunday in April and then reversed by 20 minutes on four Sundays in September, however this was revised to the simpler one-hour change that we know today.

Sadly, Willett never lived to see the passing of the Summer Time Act as he died of influenza in 1915.

Everyone appreciates the long light evenings. Everyone laments their shrinkage as the days grow shorter, and nearly everyone has given utterance to a regret that the clear bright light of early mornings, during Spring and Summer months, is so seldom seen or used.
William Willett

Daylight Saving Time (DST) has since remained to help people make better use of the daylight hours – however, it could be argued that it is more useful to some people more than others.

In 1941 during the Second World War, an emergency British Double Summer Time (BDST) was used by Britain to help with fuel shortages. This saw clocks put forward two hours ahead of GMT until the end of summer 1945. However, following a harsh winter in 1946, BDST was used again in summer 1947.

When do the clocks change in 2021?

In the UK, the clocks change twice a year, once in spring and again in autumn – usually sometime in late March and the last Sunday in October. This year the clocks change at 2am on Sunday 28 March 2021, when the clocks go forward one hour, and again at 2am on Sunday 31 October 2021 when they go back one hour – hence the phrase, ‘spring forwards, fall back’.

This change signifies the end of British Standard Time (BST), as the UK returns to Greenwich Mean Time (GMT). DST is used in most European countries, North Africa and Australasia.

What are the pros and cons of daylight saving?

Daylight saving is designed to help those who rely on daylight for work, such as farmers or labourers. For the rest of the population, it is debatable whether DST makes much difference, although it remains a divisive issue with the European parliament voting to abolish it from 2021.

In regards to health, many experts have argued DST can disrupt sleep patterns and even increase the risk of heart complications.

How to make the most of your extra hour of daylight in spring

While you initially lose an hour of sleep when the clocks go forward an hour in March, you gain an extra hour of daylight, which is handy if you work full-time and want to enjoy the longer evenings. Here are a couple of activities to enjoy in the lighter evenings.

Get stuck into gardening

Woman gardening
Plant summer bulbs in spring ©Getty

March and April are great months for getting into the garden. Plant onions, potatoes and summer bulbs, work your compost and protect emerging shoots from slugs. Stay on top of early growth by mowing the lawn (when dry), weeding and pruning bushes.

Go on a blossom walk

Pear blossom
Pear blossom ©Getty

Even after a nine-to-five there’s enough daylight to head out on a stroll and see early spring’s blossoming trees. Hawthorn’s turn white and pink with thick clusters of blossom, while later in the month wild cherry trees turn white with blousy petals. Look out for the crab apple bloom, its sweetly scented flowers an important source of early pollen for bees.