Folks, I know you all know - being brainy ARRSErs and so forth, but don't forget to put the clocks forward at 0100hrs tomorrow morning. BST is here once again. The idea of summer time, or daylight saving time, was first suggested in a whimsical article by Benjamin Franklin in 1784. In 1907 an Englishman, William Willett campaigned to advance clocks by 80 minutes, by 4 moves of 20 minutes at the beginning of the spring and summer months and to return to Greenwich Mean Time (GMT) in a similar manner in the autumn. In 1908 the House of Commons rejected a Bill to advance the clocks by one hour during the spring and summer months. Summer time was first defined in an Act of 1916 that ordained that for a certain period during the year legal time should be one hour in advance of GMT. The Summer Time Acts of 1922 to 1925 extended the period during which summer time was in force and so, from 1916 up to the Second World War, clocks were put in advance of GMT by one hour from the spring to the autumn. During the Second World War, double summer time (2 hours in advance of GMT) was introduced and was used for the period when, normally ordinary summer time would have been in force. During the winter clocks were kept one hour in advance of GMT. After the war, summer time was invoked each year from 1948 to 1967. In 1968 clocks were advanced one hour ahead of GMT on 18 February and remained so until British Standard Time, during which clocks were kept in advance of GMT all year, came into force between 27 October 1968 and 31 October 1971. The Summer Time Act 1972 defined the period of British Summer Time to start at 02.00 GMT on the morning of the day after the third Saturday in March or, if that was Easter Day, the day after the second Saturday. It was to end at 02.00 GMT on the day after the fourth Saturday in October. The duration of British Summer Time can be varied by Order of Council and in recent years has been changed so as to bring the date of the start of Summer Time into line with that used in Europe. The rule for 1981â1994 defined the start of summer time in the UK as the last Sunday in March and the end as the day following the fourth Saturday in October. The time of change was altered to 01.00 GMT. The European Union has now adopted The Ninth European Parliament and Council Directive on Summer Time Arrangements in which it states that summer (or daylight saving) time will be kept between the last Sunday in March to the last Sunday in October. Some people advocate that summer time is kept all year round but this is opposed by other groups on the grounds that in the north this would have social disadvantages including, for instance, the problem that in the far north-west of Scotland sunrise would occur at about 10.00 in the middle of winter and over much of the north small children would have to travel to/from school in darkness. Many countries around the world use daylight saving time, including the USA, Russia, most of Europe and the Commonwealth. The main reasons given for the use of summer time are the saving in power given by the longer hours of daylight in the evenings and the increased useful daylight leisure time available to those who work.