People skated 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. The UK will remain in a cold snap until the weekend.Source: PA