So when exactly do the clocks change this year? British Summer Time (BST) traditionally starts on the last Sunday in March and ends on the final Sunday in October. So clocks will go back an hour at 2am on Sunday, October 27, 2013, when BST ends and the country reverts to Greenwich Mean Time (GMT). And when do the clocks go forward and back in 2014? The dates for next year are March 30 and October 26.