When did we start changing the clocks?We started changing the clocks during the First World War, as a way of conserving energy. The original idea for British Summer Time (BST) had come from a politically connected Edwardian builder, William Willett. He argued – in a 1907 pamphlet called The Waste of Daylight – that moving daylight hours from morning to evening in summer by putting the clocks forward would improve health, happiness and productivity. The idea made it as far as parliame