The United Kingdom is not on Greenwich Mean Time (GMT) when it observes daylight saving time in the summer months in the northern hemisphere. In fact, it observes British Summer Time (BST), which is one hour ahead of GMT, in this period.
The United Kingdom moves its clocks forward by one hour during the last Sunday of March until the last Sunday of October, thus observing BST instead of GMT during this period. After the daylight saving period, the United Kingdom shifts back to GMT, which is in the same time zone as Coordinated Universal Time (UTC).
UTC/GMT does not change during the daylight saving period because it does not observe daylight saving time. Time zones around the world are expressed as positive or negative offsets from UTC. So when the United Kingdom observes BST during the daylight saving period, also known as summer time, it is one hour ahead of UTC/GMT during the summer. UTC/GMT is used all year in countries such as Iceland but it is used only during the winter months in Ireland and most the United Kingdom, which includes England, Wales, Scotland, and Northern Ireland. BST does not apply to overseas territories of the United Kingdom, such as the British Virgin Islands and Gibraltar.
People who use the Meeting Planner or The World Clock – Time Zone Converter to check time differences between cities in the United Kingdom and in other countries are advised to use London (or another major city in the United Kingdom) instead of GMT as a point of reference during the daylight saving schedule. This method helps people obtain accurate information on time differences when planning meetings or calling friends and families from overseas.
The World Clock also displays the correct time zones for cities in the United Kingdom that follow BST during the daylight saving period. This service displays a main list of cities, such as London. It also features other cities in the United Kingdom when it is shown as an expanded World Clock. These cities include: Birmingham, Liverpool, Belfast, Edinburgh, Glasgow, and Cardiff.
According to the United Kingdom’s Department of Business Enterprise & Regulatory Reform, proposals have been made from time to time about changing the United Kingdom’s time zone to Central European Time (CET). However, any changes would need to take into account the effect on business and transport links with other countries, on health and safety issues such as road traffic accidents, and on social and community life.
Although there could be some advantages, the adoption of Central European Time in the United Kingdom would result in later sunrises in winter, affecting particularly outdoor workers and people in the north of England and Scotland. There are no current plans to change the United Kingdom’s time zone. Find out more about the United Kingdom’s history on time zones and daylight saving time.
Please note that any reference to "summer" in this article relates to summer in the northern hemisphere, not the southern hemisphere.