Britain's public transport system is coming back to life after a Christmas Day closedown - but only slowly and partially. So what are the prospects for travellers with or without a car? These are the key opportunities and problems.
There is a surge in travel on Saturday 27 December as intercity services are restored. But some serious problems are disrupting trains, including:
Elsewhere, faults on trains and delayed train crews are causing further disruption. There are continuing problems on CrossCountry services. The network connects England, Wales and Scotland through the hub at Birmingham New Street. Some trains are cancelled or curtailed "due to a shortage of train drivers.
Widespread Network Rail engineering work is underway. Some key stations and lines will close, putting pressure on other routes.
No trains will run to or from the main London Liverpool Street station - the busiest in Britain - until 2 January. The exception is the Elizabeth line, which will enable travellers to reach Stratford station - where many links, including the Stansted Express, will start and end.
One of the UK's other busiest stations, London Waterloo, will be closed from the end of services on Christmas Eve to Sunday 28 December inclusive.
The West Coast Main Line, which connects London Euston with the West Midlands, northwest England, North Wales and southern Scotland, will be closed on the key stretch from Milton Keynes and Rugby up to and including 4 January. A key junction at Hanslope, south of Rugby, is being replaced. Rail replacement bus services will operate. In addition, Chiltern Railway from London Marylebone to Birmingham, the East Coast Main Line north from London King's Cross and the East Midlands line from London St Pancras will take the strain.
Further north, the West Coast Main Line between Preston and Carlisle will close from New Year's Eve to 15 January inclusive. A shuttle service will connect the two cities via the scenic Settle & Carlisle Railway.
No trains will run on the main line between Leeds and York until the start of services on 3 January.
New Year's Eve will be quiet, with New Year's Day seeing fewer travellers still - though in Scotland, almost no trains will run on 1 January.
Crowds will build back on Friday 2 January, with the final weekend of the festive season on Saturday 3 and Sunday 4 January seeing large numbers of travellers - many of them displaced to other lines by Network Rail engineering work.
The AA predicts that before the big return to work on 5 January 2026 there will be three peak days: 27, 29 and 30 December.
New Year's Day will be the quietest festive travel day.
Key locations for congestion are:
In addition, the M27 in Hampshire is closed between junctions 9 and 11 until 4am on 4 January.
Sailings have resumed to and from the Port of Dover after the Christmas Day closedown - but delays are reported in clearing the French frontier before boarding ferries. In late morning on 27 December, P&O Ferries warned: "Customers are advised there are currently large queues in the buffer zone. Please allow extra time for your journey."
The port is urging drivers not to arrive more than two hours before their scheduled departure. Unlike aviation, there is no penalty for missing a ferry at Dover due to congestion; you will simply be rebooked free of charge. "If you missed your ferry, please don't worry," the port is telling motorists. "You'll be put on the next available sailing."
In western Scotland, ferries between Mallaig and Armadale in the south of Skye have been cancelled all day. Caledonian MacBrayne blames "a technical issue with MV Lochnevis' Praxis system affecting Bow Thruster operations". The rest of the CalMac network is running largely to schedule. No Caledonian MacBrayne vessels will operate on New Year's Day.
On Saturday 27 December, the main problems are on flights to and from New York, where extreme wintry weather is causing delays and cancellations.
Hundreds of flights have been grounded overnight on Friday and on Saturday, including services between New York JFK and London Heathrow.
Under air passengers' rights rules, travellers booked on UK airline whose flights are cancelled are entitled to be flown to their destination as soon as possible on any carrier, and to be provided with meals and hotels until they get there. Those with tickets on US airlines who are trying to return from New York have no such protection.
During the 17 days of the festive spell from 19 December to 4 January, aviation analysts at Cirium report 42,046 flights are scheduled to depart from UK airports with a total of 7.8 million seats. That is an average of more than 100 take-offs per hour, with almost 20,000 seats.
Departures are up 2 per cent compared with the festive period in 2024, and available departing seats up 4 per cent year on year.
London Heathrow has the highest number of flights, with one in five departures being from the UK's busiest hub. It is expecting its busiest festive spell to date, as are Birmingham and Manchester airports.