Heavy snowfall overnight in Britain caused widespread travel delays across the country, including disruptions to flights and London's rush hour Monday morning, and forced the closure of dozens of schools.All public buses in London have been suspended because of what the city's transport authority described as dangerous road conditions. Several subway lines have been shut down and others are working with severe delays Monday.British Airways says on its Web site that "flights to and from all London airports, especially London City and Heathrow, are subject to delays and cancellations." BAA Ltd., which operates seven airports in Britain, asked passengers to check with airlines before leaving for Heathrow, Gatwick and Stansted airports.Southeast England has been hardest hit with up to 10 inches (25 centimeters) of snow reported in some areas, including the counties of Kent, Surrey and Sussex, according to the Met Office, Britain's national weather service.