Guardian: Britons have been warned to brace themselves for an increase in food prices as plunging temperatures leave farmers unable to harvest vegetables and hauliers struggle to distribute fresh produce. Gordon Brown, who will chair a meeting of the Cobra emergency committee early this week to discuss the freeze, was forced to reassure the country that it would not run out of gas or grit for its roads during the coldest weather in 30 years. Police confirmed last night that the …