1) 193 weeks(18 Feb 1968 - 31 Oct 1971)
In 1968 Harold Wilson's government decreed that Britain would shift to permament GMT+1 by not switching the clocks back an hour in October. Technically this was British Standard Time, not British Summer Time, as there was no intention to return to seasonal time adjustments. This change increased evening daylight throughout the winter months (which was popular) but also delayed sunrise (which was not, especially in Scotland). Statistics showed that road accidents decreased in the evening more than they increased in the morning, which was good, but this couldn't be pinned down solely to the time change. Ultimately permanent BST proved unpopular enough that Parliament voted to end it by 366 votes to 81, a fairly convincing rebuttal, and the annual switcheroo has continued ever since.
2) 62 weeks(25 Feb 1940 - 4 May 1941)
One great way to boost the war effort, Winston Churchill thought, would be to adjust the nation's clocks. More daylight in the evenings would improve industrial production and give workers more chance of getting home before the blackout. So a decision was taken not to move the clocks back an hour in autumn 1940, and then when spring 1941 came round they were shifted another hour onto GMT+2.
3) 34 weeks(Winter 1941 and Winter 1942)
The wartime move to Double Summer Time (GMT+2) meant that ordinary summer time (GMT+1) became the default during the winter (or, to be more exact, from mid-August to early April).
5) 33 weeks(Winter 1943 and Summer 1948)
Double Summer Time ended swiftly after VE Day in 1945, but was reintroduced in 1947 to help cope with nationwide fuel shortages after a particularly tough winter. The spring of 1947 saw the shortest ever period of British Summer Time, running for just four weeks from 16th March to 13th April. The following year things went back to normal, with a particularly early start on 14th March, and that's how 1948 got to be the longest period of summer time to coincide with a single summer.
7) 32 weeks(Summer 1967, 1972-75, 1978-80)
After the four-year Double Summer Time experiment the BST changeover dates settled down, becoming "the third weekend in March to the fourth weekend in October". That's 32 weeks in some years and 31 weeks in others, which is one week more than we get today.
15) 31 weeks(this summer and 24 others)
In 1980 the European Union issued a directive that clocks across the community would move forward an hour on the last Sunday in March and back an hour on the last Sunday in October. This is still the case, all proposals tochange the status quo having come to nothing. It means we enjoy 30 weeks of summer time 3 years out of 7 and 31 weeks of summer time 4 years out of 7, with 2022 fortunately one of the latter. Just 21 weeks to go and we'll be putting our clocks forward again...
