British Summer Time - Periods of Deviation

Periods of Deviation

In 1940, during the Second World War, the clocks in Britain were not put back by an hour at the end of Summer Time. In subsequent years, clocks continued to be advanced by one hour each spring and put back by an hour each autumn until July 1945. During these summers, therefore, Britain was two hours ahead of GMT and operating on British Double Summer Time (BDST). The clocks were brought back in line with GMT at the end of summer in 1945. In 1947, due to severe fuel shortages, clocks were advanced by one hour on two occasions during the spring, and put back by one hour on two occasions during the autumn, meaning that Britain was back on BDST during that summer.

An inquiry during the winter of 1959–60, in which 180 national organisations were consulted, revealed a slight preference for a change to all-year GMT+1, but the length of summer time was extended as a trial rather than the domestic use of Greenwich Mean Time abolished. A further inquiry during 1966–67 led the government of Harold Wilson to introduce the British Standard Time experiment, with Britain remaining on GMT+1 throughout the year. This took place between 27 October 1968 and 31 October 1971, when there was a reversion to the previous arrangement.

Analysis of accident data for the first two years of the experiment indicated that while there had been an increase in casualties in the morning, there had been a substantially greater decrease in casualties in the evening, with a total of around 2,700 fewer people killed and seriously injured during the first two winters of the experiment, at a time when about 1,000 people a day were killed or seriously injured on the roads. However the period coincided with the introduction of Drink-Driving legislation, and the estimates were later modified downwards in 1989.

The trial was the subject of a House of Commons debate on 2 December 1970 when, on a free vote, the House of Commons voted to end the experiment by 366 to 81 votes.