Portugal used CET in the years 1966–1976 and 1992–1996.
The time around the world is based on Universal Coordinated Time (UTC) which is roughly synonymous with Greenwich Mean Time (GMT). From late March to late October, clocks in the United Kingdom are put forward by one hour for British Summer Time (BST). Since 1997, most of the European Union aligned with the British standards for BST. Central European Time is thus always one hour ahead of British time.
In 1968 there was a three-year experiment called British Standard Time, when the UK and Ireland experimentally employed British Summer Time (GMT+1) all year round; clocks were put forward in March 1968 and not put back until October 1971.
Central European Summer Time
The following countries and cities have introduced the use of Central European Summer Time (UTC+02:00) between 1:00 UTC on the last Sunday of March, and 1:00 UTC on the last Sunday of October:
Discrepancies between official CET and geographical CET
Legal time vs local mean time
1 h ± 30 m behind
0 h ± 30 m
1 h ± 30 m ahead
2 h ± 30 m ahead
3 h ± 30 m ahead
Legal, political and economic, as well as physical or geographical criteria are used in the drawing of time zones so official time zones rarely adhere to meridian lines. The CET time zone, were it drawn by purely geographical terms, would consist of exactly the area between meridians 7°30′ E and 22°30′ E. As a result, there are European locales that despite lying in an area with a "physical" UTC+1 time, actually use another time zone (UTC+2 in particular – there are no "physical" UTC+1 areas that employ UTC). Conversely, there are European areas that have gone for UTC+1, even though their "physical" time zone is UTC (typically), UTC-1 (westernmost Spain), or UTC+2 (e.g. the very easternmost parts of Norway, Sweden, Poland and Serbia). On the other hand, the people in Spain still have all work and meal hours one hour later than France and Germany even if they have the same time zone. Following is a list of such "incongruences":
Historically Gibraltar maintained UTC+1 all year until the opening of the land frontier with Spain in 1982 when it followed its neighbour and introduced CEST.
Areas located within UTC+1 longitudes using other time zones
Areas between 7°30′ E and 22°30′ E ("physical" UTC+1), all using UTC+2
Map of Petsamo area in northern Finland/Soviet Union/Russia. The green area is the Finnish part of the Rybachi peninsula (Kalastajasaarento) which was ceded to the Soviet Union after the Winter War. The Red area is the Jäniskoski-Niskakoski area ceded to the SU 1947.
The northeast of Norway, lying north of Finland, roughly coinciding with the county of Finnmark; for instance Vadsø, the capital of Finnmark, has a longitude of 29°49′ E. Actually, the easternmost town in Norway, Vardø, lies at 30°51′ E, which is so far east, so as to be east even of the central meridian of EET (UTC+2), i.e. east of Istanbul and Alexandria. The sun reaches its highest point at 10:56 (when not DST). The Norwegian-Russian border (incl. border passings such as Kirkenes) is the only place where CET (UTC+1/+2) borders Moscow time (UTC+4), resulting in a two hours time change (or three hours in winter) for the passenger crossing that border.
More so, there exists a "tri-zone" point (where UTC+1, UTC+2, and UTC+4 meet) at the Norway-Finland-Russia tripoint near Nautsi. It is interesting to perform the following mental experiment when looking at this map: Go to the westernmost point of the red area (the Jäniskoski-Niskakoski area); this belongs to Russian jurisdiction, hence the time there is UTC+4 (formerly UTC+3). Then, take a northeastern (NE) direction (that is an eastwards direction); you will soon be crossing into Finnish territory, thus moving to the UTC+2 time zone. Continuing in that direction, you will eventually reach the Finland-Norway border and enter Norway, thus passing into the UTC+1 time zone. So, moving in a (north–)easterly direction, you will be moving from UTC+4 to UTC+2 to UTC+1.