Watch as people take to the ice to skate on a frozen flooded field in Upware, Cambridgeshire, on Thursday 18 January. The Cambridgeshire Fens were the birthplace of British speed skating and require four nights of frost, with a temperature of -4C or colder and little or no thawing during the days in between, to make ice strong enough to skate on. Fen skating takes place when a meadow floods and then freezes over, so the ice is very shallow, in some places just a few centimetres. Much of the UK endured temperatures below freezing overnight.