In autumn 2019 the clocks will go back on 27 October at 2am. On the last Sunday of October the clocks ‘fall back’: they go back by one hour. It may feel like a long time since the blue skies of summer, but this marks the end of British Summer Time (BST). It also means an extra hour in bed.
https://www.rmg.co.uk/discover/explore/when-do-clocks-go-back

