This is when the clocks change this month and why we have British Summer Time

But we will get a dreamy extra hour in bed (unless you use that time to change your clocks).

Anyway, this is why we get that hour – and why it’s sometimes cruelly taken away:

When will the clocks go back?

October 27 2019. For future reference, it always takes place on the last Sunday in October. The clocks will go back one hour at 2am, so sweet dreams.

This will mean Portsmouth and the rest of the UK is on Greenwich Mean Time (GMT), which is the standard time zone against which all other time zones in the world are referenced.

The reason it happens on a weekend, in the middle of the night, is to limit the disruption for schools and businesses.

When do the clocks go forward?

On the last Sunday in March – this year it was March 31 – the clocks go forwards one hour at 1am, starting the period of British Summer Time (BST) aka Daylight Saving Time (DST).

This gives us more daylight in the evenings. And one less hour in bed.

Why do we bother changing the clocks?

Initially it was rolled out to save energy and get people outside. Why waste electricity when there is perfectly good daylight to be used?

The campaign for British Summer Time came about at the beginning of the 20th century. Moving the clocks forward in the summer months would give us darker mornings but lighter, longer evenings.

The idea was proposed in Britain by builder William Willett, says Dr Richard Dunn, senior curator for the History of Science at the Royal Observatory Greenwich.

Willett was ‘incensed at the “waste” of useful daylight during the summer. Though the sun had been up for hours as he rode his horse through Chislehurst and Petts Wood, people were still asleep in bed.’

British Summer Time was adopted in Britain in 1916 to save fuel and money.

Since then, Britain toyed with moving the clocks a number of times, including bringing them forward two hours ahead of GMT during the Second World War. They were also brought forward for periods in the spring of 1947, in line with fuel shortages.

There was an experiment, between 1968 and 1971, which kept clocks one hour ahead of GMT all year round.

Britain then reverted to our now familiar system of GMT in the winter and summer time in between March and October.