Britain's Big Freeze is gripping the north with conditions so bad in places that the Met Office has issued an emergency weather warning. Weathermen have warned that more than a foot of snow could fall in northern England and in Scotland. The blizzards are thought to have cost the economy as much as £3 billion as London and other major cities ground to a halt. Children across Britain are getting another day off school after thousands of schools and colleges remain closed for a second day. Air passengers face a second day of flight cancellations and delays as more snow fell overnight and travellers are advised by airport operator BAA to check with their airlines before setting off. A limited train service resumed today for commuters in Kent and East Sussex coming into London. Operator Southeastern advised travellers to expect some delays and allow extra time to complete their journeys. Passengers were also warned of slippery conditions underfoot, particularly at smaller unstaffed stations. A Southeastern spokeswoman said: "We're aiming to run a limited service today, mostly half-hourly for the majority of routes, with some more remote locations operating an hourly service, so if people want to travel they can travel." Forecaster Claire Austin said: "Northern England and Scotland will be having lots of snow, mainly on higher ground, with sleet and rain elsewhere." She added: "The snow will also come to west Wales and south-west England. As the day goes on northern England will get drier but the rain will stay in Scotland and fall as snow over higher ground. Northern Ireland will stay wet. "Wales and south-west England will have wintry showers with a mixture of sleet, snow and a bit of hail. The rest of the country will stay pretty much dry." Low temperatures are expected to continue across parts of the UK, with highs of just 1C (34F) in some areas of northern England, rising to a maximum of 5C (41F) in London and Kent, where it is expected to become drier through the day.