Backward / Forward movements of time in the UK

When?
1) In the UK, we all change our clocks and watches by one hour, twice a year.
• Last Sunday in March
We add an hour and go onto what is called British Summer Time (BST).
• Last Sunday in October
We put our clocks back one hour and adhere to Greenwich Mean Time (GMT).

2) Clocks move backwards one hour.
Sunday 25 October 02:00 BST changed to 01:00 GMT.

Why?
- to save mornings light in during the summer
We've been changing our clocks forwards and backwards in the UK since 1916. It's all to do with saving the hours of daylight, and was started by a man called William Willett, a London builder, who lived in Petts Wood in Kent (near our school).
William Willett first proposed the idea of British Summer Time in 1907 in a pamphlet entitled 'The Waste of Daylight'. Willett had noticed that the summer mornings light was wasted while people slept, and that the time would be better utilised in the afternoon by putting the clocks forward. After campaigning for years the British Government finally adopted the system a year after Willett's death.

Other countries?
European Union - Most countries change their clocks on the last Sundays of March and October.
North America and most of Canada on the second Sunday in March and the first Sunday in November.
Egypt, Namibia and Tunisia are the only African countries who observe daylight saving.
New Zealand and parts of Australia are the only countries in Oceania that currently put their clocks forwards and backwards.

Source: http://www.woodlands-junior.kent.sch.uk/customs/questions/clocks.htm