The bad weather, which is expected to continue today in the South, led to numerous accidents as drivers ignored warnings to slow down. The AA said motorways out of London were all congested with cars moving at little more than 10mph. A journey to Readingon the M4 was taking three hours.
Traffic flows from the South and East to the North and West are forecast to be lighter today but temperatures will not rise above freezing in large parts of the South and Midlands.
Poor visibility also badly disrupted flights from Heathrow, Gatwick and Stansted airports yesterday on one of the busiest days of the holiday period. Nearly 3 million people - 8.5 per cent more than last year - are expected to pass through the country's airports before 3 January About 160,000 flew from Heathrow yesterday.
A coach carrying passengers from a flight from Bucharest and Berne, which had been diverted to Luton from Stansted, crashed on the M1 in Hertfordshire injuring 11 people, all Romanians. The coach overturned and slid down an embankment. Thames Valley Police said that by early evening there had already been more than 50 minor crashes in its region.
Temperatures overnight were forecast to drop to -7C and are unlikely to rise above -2C or -3C where the fog fails to lift. Major roads have been salted but smaller roads were said to be like ice-rinks. An AA spokesman said: "They are all going mad. People are driving too fast without lights in the fog.''
Traffic volumes were made worse by last-minute Christmas shoppers. "There will be record sales," a spokeswoman for the British Retail Consortium said. "People are spending more than last year but they are not being extravagant."
The London Weather Centre predicted milder weather for Christmas Day with outbreaks of rain. Sunshine and showers are forecast for Boxing Day.