Arctic conditions have meant a miserable return to work for millions of shivering Britons. Icy rain, sleet and snow moved down the UK, turning to ice in many places as temperatures dropped overnight. The Met Office issued a severe weather warning for London and east and south-east England with widespread icy roads and pavements. Meanwhile, people living in those areas could wake to one to two centimetres of snow. "It's going to be a bitterly cold morning," said forecaster Dan Adamson. "It's been a few years since it's been as cold as this." December 30 saw temperatures plummet to -13C in the Scottish Highlands, while on Saturday night Benson in Oxfordshire reached -9, he said. Though temperatures dropped below zero in most places last night, cloud cover meant it was not as cold as Saturday night. The current cold snap is set to continue until the weekend when milder weather may finally arrive. The chill prompted water company Severn Trent to appeal to its eight million customers across the Midlands and Wales to protect their water systems, after receiving reports that pipes were freezing even with heating on full blast. Health campaigners have warned that the return to work this week will prove "heavy going" for the NHS with many people laid low by the spread of the winter vomiting virus and flu. Businesses and schools will also be affected as people call in sick and those employees who do struggle in to work are more likely to spread bugs around offices and factories. Geoff Martin, from campaign group Health Emergency, said: "The period after Christmas and New Year is always heavy going for hospitals as the country gets back into gear but the return of the icy weather, along with the flu and the norovirus, is likely to pile on the pressure. "We know from front-line reports that services in many areas are dangerously short of capacity and are working on a knife edge. "In the north west, the service is paying a heavy price for the closure of Burnley's A&E department and bed reductions elsewhere have left the NHS dangerously exposed this winter."