The threat of heavy snow is continuing to linger over rail, road and air passengers in England as the severe weather persists.
Met Office heavy snow warnings remain in place for the East, London, the South East and the East Midlands.
Gatwick Airport re-opened safely on Friday morning, although flights remained suspended at other airports.
Transport Secretary Philip Hammond announced a review into travel chaos as trains and roads ground to a halt.
Forecasters said around 15in (38cm) of snow had fallen in Redesdale, Northumberland, while another 10in (25cm) fell in Charlwood, West Sussex.
Temperatures were expected to plummet further overnight, possibly dipping below -12C in London and the South East. At Brough in East Yorkshire, nine inches (23cm) of snow fell overnight, while more than 150 schools across Derbyshire and East Staffordshire remained closed. In Kent, more than 300 schools were closed.
Flights have been suspended at Humberside Airport until 0730 GMT and Durham Tees Valley Airport has also been closed.
Bournemouth Airport has been closed until 0800 GMT and there were delays and cancellations at London City Airport.
Most flights were operating from Heathrow Airport but there were some delays and cancellations due to snow disruption at other airports.
Snow in Sheffield city centre was 38cm (15in) deep on Thursday - the most recorded in December since records began in 1882.
In Nottinghamshire, the county's coroner urged carers and neighbours to check on elderly people after seven cold-related deaths in the past week.
In Northumberland, fire crews were called after a shed collapsed under the weight of snow on its roof in Newton-on-the-Moor, trapping more than 200 sheep and cattle.
South Central Ambulance Service NHS Trust attended 27 medical emergencies where people have fallen on ice in Oxfordshire and Buckinghamshire in the space of 36 hours.
In Hampshire, a gritting lorry added to the traffic problems when it overturned as it cleared the A3, near Petersfield.
More than 100 drivers spent a second night stranded on the A57 in South Yorkshire overnight while 300 rail passengers spent the night on a train at Three Bridges station in West Sussex after a series of line failures stalled three trains.
They waited on the platform for about an hour before getting on a heated train, where food and drink from all-night garages was provided by station workers.
"It was an absolute nightmare," said passenger Rebecca Forsey.
"We had to wait around for several hours in the cold on a freezing platform. We finally got something to eat at 4am, so that's good."
Union leaders urged the government to suspend planned rail fare increases next month after accusing train companies of "failing" to deliver services because of the snow.
The Rail Maritime and Transport union said travellers in some of the most affected areas faced the biggest increases.
Industry watchdog Passenger Focus urged rail companies to investigate "what went wrong".
Many trains serving London Victoria, Charing Cross and Cannon Street were cancelled or delayed and Eurostar was delayed by up to 90 minutes.
There was also disruption on First Hull Trains, CrossCountry and East Midlands train services.
Southern Railway and Southeastern both said they would be running a much reduced service on Friday.
Announcing an urgent review into how transport operators have coped with the wintry weather, Mr Hammond said complacency was "not an option".
"We took urgent action during the summer which means we're better prepared for severe weather than last year - a national strategic salt reserve exists for the first time," he said.
"But I share the frustration of the travelling public and we need to be sure that we are doing everything possible to keep Britain moving."
The Association of Train Operating Companies said rail operators and Network Rail were "doing all they can to keep trains moving and get people to where they need to be".