Why do the Clocks Change?

When and why do the clocks change?

The clocks change twice a year in the UK in Spring and in Autumn. The clocks go forward 1 hour on the last Sunday in March and backwards 1 hour on the last Sunday in October. The period when the clocks are 1 hour ahead is called British Summer Time (BST). When the clocks go backwards, the UK is on Greenwich Mean Time (GMT). The clock change allows the UK to enjoy more daylight hours especially during the winter.

However the countries closer to the equator have less variation in daylight hours, for example, many countries especially around the equator don’t change clocks at all because the amount of daylight they have doesn’t really change over the year. In places further to the North of the equator like the UK, Scandinavia or North America the seasonal variations are more noticeable because of the tilt of the Earth’s axis which means they get more daylight in the summer and less in the winter. 

So therefore the further North or South of the equator you are the more the seasonal differences in the daylight hours there are. That is why the places far North and South for half of the year see almost no daylight at all. In the UK, Scotland will see more average daylight hours than the south of England in the summer and less in the winter.

That is the reason we change clocks in the UK to make better use of natural daylight.

How did people use to measure time over the years?

People have been using the sun, the moon and the stars to measure time from the earliest days and one of the oldest instruments for telling the time was sundials. Other ways include oil lamps, candles, hourglasses (sandglasses), and water clocks.   

The sundials were used until the mid-19th century and many towns kept their own local time using the sun as a guide. Some UK towns and cities still have sundials in cathedrals, churches and stately homes.

Why the time became standardised?

The UK has been one of the first countries that standardised the time to Greenwich Mean Time or GMT. This happened when the railway network become more widespread and timekeeping become more important to make it easier for the rail workers and passengers to understand and follow the train timetables. GMT became the legal standard time in 1880 even though there are regional differences in what’s known as local noon.