The Great Clock Springs Forward

This blog post was written by Verity Jones, Assistant Archivist (Graduate Trainee).

On the 29th March, the clocks will go forward one hour, meaning the end of Greenwich Mean Time and the official start of British Summer Time.

At this time of year, most of us are eagerly anticipating the lighter evenings (and hopefully some warmer weather!). But for the clockmakers who take care of the Great Clock in Elizabeth Tower, Saturday night will consist of careful precision and split-second timing. ‘Spring forward, fall back’ has become a staple in British culture for marking the changing of the seasons, but it wasn’t always such a familiar concept. With the help of the collections here at the Parliamentary Archives, read on to learn about the history of British Summer Time, and the way it impacts the Great Clock twice a year.

Greenwich Mean Time, the time Britain now follows during the winter months, was the first standardised time zone in Britain. Before the mid-1800s, most towns kept their own local time as defined by the sun. This meant there was no way of defining the start or end of a day, or knowing how long an hour should be. With the expansion of the railways, it became necessary for a national time standard to be set, so that timetables could be properly understood. The railways chose Greenwich Mean Time, leading to nearly all public clocks in Britain being set to GMT by the mid-1850s. It officially became Britain’s legal standard time in 1880, in the Definition of Time Act.

While the standardisation of time had many benefits for Britain, the new system meant that in summer the sun would rise at 3am and set at 9pm. Arguments soon arose that daylight was wasted that early in the morning, and the darker evenings meant that fuel was wasted on lighting homes. By the start of the 20th Century, campaigners were pushing for the clocks to go forward in summer, to allow for lighter evenings and darker mornings. One of the most vocal campaigners was William Willett, a builder who self-published the pamphlet ‘The Waste of Daylight’ in 1907. He suggested that the clocks should go forward in 20 minutes intervals over successive Sundays in April and reversed in the same way during September. His idea was ridiculed, and a Daylight Saving Bill was rejected in 1909.

However, after the outbreak of WWI in 1914, European countries were keen to conserve fuel supplies. Germany and Austria first introduced Daylight Saving hours in 1916. Britain quickly followed, introducing the Summer Time Act of 1916, which came under the Defence of the Realm Act. Sadly, Willett never saw his idea implemented, having passed away in 1915. After the war, the act remained, meaning that British Summer Time continued to be observed. During WWII, the government even moved to British Double Summer Time, when the clocks were permanently set to BST, with an extra hour added during the summer months. This meant that in summer, the clocks were two hours ahead of GMT.

British Summer Time is still used today, so the Great Clock in Elizabeth Tower needs to be changed twice a year. There is a strict schedule to ensure the change always goes smoothly. During the evening, Big Ben is silenced. Next, the dial light is turned off and the hands are wound round to midnight to await the time change. It is very important that the hands do not go past midnight, or else they would have to be wound all the way round to twelve again! The clock is restarted two hours before the time change. This allows the clockmakers to ensure it is running smoothly and to allow for any adjustments. Then, when the clocks spring forward, the lights are returned, and the Great Bell strikes the hour. The clockmakers also have 2000 other clocks across the Parliamentary Estate which must be changed over the course of the weekend!

This year, on the same night that the clocks go forward, the Elizabeth Tower will also mark Earth Hour. Between 8.30pm and 9.30pm, landmarks across the world, including Elizabeth Tower, will go dark to highlight the threat of climate change. Then, just a few hours later, the clockmakers will be busy ensuring the clock shows the right time for the start of spring. So, while you’re enjoying the sunshine this summer, spare a thought for the people in Elizabeth Tower, making sure London’s most iconic clock is keeping up!