Cold weather causes travel disruption across the UK
Traffic in the Home Counties ground to a halt amid ice and slush
Winter weather is continuing to cause disruption across the UK with road, rail and air travel all affected.
Channel Tunnel services remain badly affected after Eurotunnel closed its car shuttle service to new passengers.
British Airways cancelled all European and UK domestic flights leaving Heathrow after 1900 GMT.
Many roads in the Home Counties are gridlocked and the AA said London and the South East were hotspots for vehicle breakdowns.
Luton airport is closed until 0030 GMT and London City airport is shut. Stansted airport is open but flights may be subject to delays or cancellations.
Easyjet said it had operated over 80% of its flights, "albeit with some delays", over the last five days despite the weather, but added that further snow on Monday night could result in continued flight disruptions.
A Met Office severe weather warning is in place for ice in many parts of the UK, where snow freezing on the ground is causing treacherous conditions.
Temperatures are expected to fall to 1C (34F) in central London overnight, -4C (25F) in Newcastle, -3C (27F) in Glasgow, -4C in Manchester and -1C (30F) in Cardiff.
In Wales, 180 schools and nurseries had to close, while the M4 was shut after a crash.
Many minor roads are treacherous - they're like ice rinks - with numerous shunts and cars stuck in ditches
Up to 5cm (2in) more snow is expected in the south and east of England, spanning from Lincolnshire down through Hampshire, followed by freezing conditions.
The weather had its greatest impact on Channel Tunnel services, where Eurostar cancelled trains to mainland Europe for the third day, while Eurotunnel closed its shuttle car service to new arrivals after its Folkestone terminal reached "saturation point".
Eurostar said it hoped to resume a limited service on Tuesday.
Passengers at Heathrow's Terminal 5 have reported large queues as people attempt to make alternative arrangements following BA's decision to stop its evening flights.
People are said to have been offered coach trips to places such as Newcastle to replace their cancelled flights.
At Manchester Airport, where flights were suspended overnight, the backlog of flights had been cleared by Monday afternoon.
Passengers at Bristol and Southampton airports have also experienced delays.
Bad weather in North America and Europe delayed flights arriving at Heathrow and Gatwick airports for up to six hours.
A spokesman for Gatwick said the runway had re-opened at 1954 GMT - having closed at 1519 GMT - and that staff were now working to get through the backlog of flights but the most affected airline, Easyjet, had cancelled a number of services.
Passengers travelling from Gatwick are advised to allow extra time for their journey to the airport and contact their airline for the latest flight information.
Passengers intending to use Luton airport are advised to contact their airline for more information.
Aberdeen and Inverness airports reopened after being closed on Monday morning, but delays and cancellations continued at both airports, and at Glasgow airport.
Domestic rail services across the UK were delayed and buses replaced trains in many areas.
Southeastern trains said it would be operating a Saturday timetable service on mainline, metro and high-speed routes on Tuesday, with a normal weekday service for Thameslink trains run via Blackfriars.
The company said there would be additional high-speed services through the day and a shuttle service between London Bridge and Cannon Street during the morning and evening peak times.
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