During World War II, Britain retained the hour's advance on GMT at the start of the winter of 1940 and continued advancing the clocks by an extra hour during summer until July 1945. During these summers, Britain was 2 hours ahead of GMT and operating on British Double Summer Time. The clocks were reverted to GMT at the end of the summer of 1945. In 1947 owing to severe fuel shortages, the clocks were advanced by one hour twice during the spring and put back twice during the autumn so that Britain was back on BDST during the height of the summer.[3]
An inquiry during the winter of 1959–60 consulted 180 national organisations, and had 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.[4] 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,[5] at a time when about 1,000 people a day were killed or seriously injured on the roads.[6] The period coincided with the introduction of Drink-Driving legislation though, and the estimates were later modified downwards in 1989.[5]
The trial was the subject of a House of Commons debate on 2 December 1970[7] when on a free vote, the House of Commons voted to end the experiment by 366 to 81 votes.[8]