Western European Time (WET, UTC+0, and commonly known as Greenwich Mean Time in the United Kingdom) is the time zone covering parts of western and northwestern Europe, including the following countries and regions:
During winter months, the countries above use WET, which corresponds to Universal Time (UTC); however in the summer, most (but not all) of the above places move one hour ahead to Western European Summer Time (UTC+1). Officially the Republic of Ireland is on UTC+1, but goes to UTC in winter, and for all practical purposes uses the same time as the United Kingdom. There have been calls recently for the UK, particularly England and Wales, to change to CET.
This time zone (GMT) was used in:
In the United Kingdom in years 1940-45 British Summer Time (BST=CET) was used in winters and in years 1941-45 & 1947 British Double Summer Time (BDST=CEST) was used in summers. Between 18 February 1968 and 31 October 1971 BST was used all year round.
In the Republic of Ireland in years 1940-46 Irish Summer Time (IST=CET) was used all year (Ireland did not adopt similar time changes to British Double Summer Time (BDST=CEST) in 1941-45, 1947). Between 18 February 1968 and 31 October 1971 Irish Standard Time was used all year round.
In Portugal, CET was used in the periods 1966-1976 and 1992-1996.