Why are the dates when we switch between summer and winter times (for example swapping between Greenwich Mean Time and British Summer Time in the UK) placed so asymmetrically around the solstices?
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• Earlier replies didn’t explain why the dates we switch between summer and winter times are at different distances from the spring and autumn equinoxes. It is because the seasons, and their warmth, lag behind the sun. Early March is usually colder, with an increased chance of morning frosts and ice, than late September. But in Europe there is more to it.
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While summer time was used widely in Europe during the first and second world wars to conserve energy, only the UK and Republic of Ireland maintained the system in the long term until the 1970s oil crisis. Then other European countries switched to save fuel for lighting and similar (though France and the Benelux countries were already on German time from 1940).
The UK originally changed clocks in late March and late September. Eventually agreement was reached within the EU to align time changes, making them late March and late October. Other interesting anomalies are that before the second world war Italy was on Etna Time, which by happy chance was the same as Central European Time. And the pre-war Dutch observed Amsterdam Time, 20 minutes ahead of Greenwich Mean Time.
Duncan Stewart, Henllan, Denbighshire, UK
• There is a popular misconception that daylight saving time was introduced to the UK for agricultural workers. The idea was championed in 1908 by William Willett, a keen early morning horseman who felt we were wasting precious daylight.
When it began in 1916, the stated reason was to ameliorate the wartime shortage of coal and oil for lighting and followed a similar move by Germany.
During the second world war, the UK brought in double summer time as a fuel-saving exercise, although there was propaganda suggesting it was beneficial to agriculture. My father was a farmer and told me, as any farmer will, that their days are governed by the sun, not a clock. Cows don’t work to the milk train’s timetable.
Richard Lucas, Camberley, Surrey, UK
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