Heavy snowfall sees Met Office put Britain on high alert

Roads and rail lines brought to a standstill and power supplies under threat as previously unaffected areas brace themselves for big freeze

Millions of people living in southern England and the Home Counties were told to prepare themselves for up to 40cm (16in) of snow last night, as Britain remained in the grip of the longest prolonged spell of cold weather in 30 years.

The Met Office issued its highest level of alert, warning of an impending "extreme weather event" that would bring travel chaos and threaten power supplies. Worst hit overnight will be Dorset, Wiltshire, Hampshire, Berkshire and Oxfordshire – parts of which have not seen any snow since the arctic weather began before Christmas.

Forecasters said it would be snowing in London before dawn, bringing widespread disruption to the capital and forcing many workers to stay at home. Last night, all flights were suspended from Luton, Southampton, Gatwick and Birmingham airports.

The Met Office said the freezing conditions were expected to continue for up to two weeks. A meteorologist said: "This type of warning is very rare. A period of exceptionally heavy snowfall is expected, with accumulations of 15 to 30cm and perhaps in excess of 40cm."

Heavy snow fell across northern England and Scotland yesterday, closing airports and shutting schools, while many motorways ground to a halt and smaller routes remained impassable. Bus services in Sheffield and other parts of South Yorkshire were suspended, leaving thousands without any means of transport. Temperatures plunged to a low of minus 14C in Scotland, and 29cm of snow fell in Spadeadam, Cumbria.

The National Grid also issued an alert urging power suppliers to use less gas as it tried to find more supplies from overseas to meet a 30 per cent rise in demand. Gordon Brown and the Business Secretary, Lord Mandelson, sought to ease fears that Britain was running out of power, insisting reserves would last through the cold snap, but the shadow Energy Secretary, Greg Clark, claimed the UK had just eight days of gas remaining. The Prime Minister said: "I think Britain can deal with these problems. There are always difficulties when we have a long spell of bad weather. But we can cope."

All schools in Aberdeenshire, Dumfries and Galloway and the Borders were shut yesterday, and students across the North of England, Wales and Cornwall were also sent home. The freezing weather created a child-care crisis: Amanda Coxen of the nanny agency Tinies said her company had a 50 per cent increase in inquiries, while emergencychild-care.co.uk reported a five-fold increase in bookings.

A six-year-old boy was rescued and taken to hospital after falling through ice in a garden pond while playing with a friend. It is thought he had been underwater for half an hour before he was pulled out by firefighters. Last night he was in a critical condition in Oxford's John Radcliffe Hospital, with his parents by his side.

Fears were mounting for the safety of Ian Simpkin, 36, from Wath near Ripon in North Yorkshire, who left home on foot on Sunday morning and has not been seen since. And in Derbyshire, two 13-year-old boys had to be rescued by firefighters from an island in the middle of a frozen lake.

A lorry driver was killed in a collision on the M60 in Manchester in treacherous driving conditions, while a 44-year-old man was treated for shock after his car skidded on snow into the path of a train on a level-crossing near Selby, North Yorkshire. He was able to scramble out and avoid the oncoming train just before it hit his vehicle.

There were also concerns over a shortage of grit, despite assurances from councils that stocks would be sufficient. Staff at Cheshire's Winsford salt mine said they would work around the clock to help keep the roads open.

But not everyone was pulling together – residents at Market Weighton in East Yorkshire said that thieves were emptying their grit bins as soon as they were filled. An independent councillor in Wigan hired his own grit supplies after hearing complaints from locals about slippery pavements.

The bad weather did, however, provide a boost to shops and supermarkets. Tesco said soup sales were up 80 per cent, while B&Q said demand for wellies had doubled. Halfords reported a 22 per cent rise in sales of sleeping-bags – bought by motorists fearful of being stranded in their cars.

There was more bad news for the husband of a woman, Kay Ure, who became cut off from her remote home in a lighthouse keeper's cottage at Cape Wrath in the Scottish Highlands after she ventured out to buy a turkey two days before Christmas. John Ure's generator has broken down, leaving him to rely on logs for heat and candles for light until the weather eases.

But those able to get out and enjoy the weather did so in style, with naked sledgers posting footage of themselves braving the chill on YouTube.

Sea ice and snowdrifts: Bitter British winters

1962-63 The coldest winter for 200 years left the sea frozen in places. Wales and South-west England had snowdrifts up to 6m deep and the mercury dropped to -22.C in Braemar, Scotland, on 18 January. The cold spell lasted into early March.

1946-47 Snowdrifts 7m deep cut off thousands of people. Power stations closed because of a lack of fuel; TV broadcasts were suspended. The freeze hit the economy, barely recovering from war, and contributed to an atmosphere of shortage and austerity. Snow fell somewhere in the UK for 55 continuous days between January and March.

1739-40 Severe cold destroyed potato seeds in Ireland, causing the great potato famine of 1741. The sea froze around English and Irish ports, halting the shipment of coal. People desperate for firewood stripped hedges bare; 14 men were arrested for felling trees in Dublin's Phoenix Park.

1684 The Thames froze for two months. Frost caused trees to split. The lack of running water halted production in breweries.