British Summer Time (BST)

What is British Summer Time (BST)?

British Summer Time marks the beginning and the end of the official summer season.

BST is calculated by putting Greenwich Mean Time (GMT) forward one hour at the start of the period and removing one hour at the end.

The purpose of the shift is to make maximum use of daylight hours, principally to maximise commercial efficiency. The idea was first introduced to save on fuel costs by increasing the working hours available in daylight.


Greenwich Mean Time (GMT) was established in 1884 at the International Meridian Conference, when it was decided to the place the Prime Meridian at Greenwich, England.

BST was first given a statutory footing in the UK through the Summertime Act 1916, and has undergone a number of changes since, principally because of periods of conflict and European guidance.

The Summertime Act 1972 sets out the current method of calculation. It followed a trial period from 1968-71 of equalising GMT with Central European Time (CET).

However, since 1981 EC Directives have prescribed the start and end dates of summer time in all Member States, and consequently Orders have been made in the UK to implement the new requirements.

In 2002 the British Summer Time Order amended the 1972 Act to permanently harmonise the BST dates in the UK with the rest of Europe.


The use of BST and the way it is calculated are both controversial for a number of reasons.

Firstly, some believe the system increases the number of accidents, both because of the loss of sleep when the clocks go forward and, conversely, the lack of sunlight in the evenings contributing to more accidents.

The Royal Society for the Prevention of Accidents (RoSPA) has for some time been calling for 'single-double summer time' (SDST) to be adopted; i.e. GMT + one hour from October to March and GMT + two hours from March to October. This would put the UK into the Central European Time Zone. According to RoSPA, recent research shows that adopting SDST would save around 80 lives and 212 serious injuries a year.

The 1968/71 experiment, when BST was employed all year round, was estimated to have resulted in 2500 fewer deaths and serious injuries each year of the trial period. However, the proposals were heavily defeated by MPs, with particular lobbying from agricultural groups and Scottish farmers, who warned of a reduction in working hours and claimed the switch would have a detrimental effect on their livestock, who would be unable to adjust to the change.

Indeed, there is a marked polarisation of views on the matter between Scotland and England and some have suggested that Scotland should operate on a separate time zone to the UK in order to facilitate a change.

A private member's bill introduced to Parliament in 2010 proposed that a cross-departmental analysis be carried out to assess the potential costs and benefits of putting the clocks forward by one hour for all, or part of, the year. If thought beneficial, then a three year trial period would follow to assess the full implications.

However, the bill, sponsored by Tory MP Rebecca Harris, met with considerable opposition in the Commons and eventually ran out of time during its report stage in January 2012.


Clocks in the UK went back on Greenwich Mean Time on 30th October 2011.
Clocks go forward on to British Summer Time on 25th March 2012.
Clocks go back on Greenwich Mean Time on 28 October 2012.

Source: – 2012


"Proposals have been made from time to time about changing the UK's time zone to Central European Time. However, any changes would need to have full regard to the effect on:

business and transport links with other countries ;
health and safety issues such as road traffic accidents;
social and community life.

Although there could be some advantages, adoption of Central European Time in the UK would result in later sunrise in winter, affecting particularly outdoor workers and people in the north of England and Scotland.

There are no current plans to change the UK's time zone."

Department for Business, Innovation and Skills (BIS) – 2012