Turning now to the weather and the wintry conditions that are affecting some of Scotland's main commuter routes.

Forecasters say up to 20cm of snow could fall on high ground with a weather warning upgraded from yellow to amber.

Snow and ice is forecast for much of Scotland, but the worst is expected in parts of the central belt around Glasgow and Stirling

The Met Office says travel delays and power cuts are likely in the worst affected areas and Police Scotland has urged motorists to drive carefully.

A yellow warning for snow and ice covers much of the rest of Scotland and runs until 21:00.

Our colleagues in Scotland are covering the latest here.

Katy Austin
Transport correspondent

At Southampton, there are some trains today, but fewer than normal. And today, it’s the end of the line, nothing is running south to Dorset.

Services started late. The first train from here to London Waterloo left at 7:30am. And they’ll finish early; the last direct train back from London departs at 5pm.

Outside the station, about a dozen workers were out on the picket line with their banners, from soon after 7am.

Most passengers I spoke to as they turned up to catch the trains that are running had grown used to strikes by now, and planned around it.

A few said they had great sympathy with the striking workers, despite the inconvenience.

But others did not know there was another strike today and weren’t sure if their usual trains would be running to get them to appointments. One student trying to get to their sixth form college told me strikes had added stress at a busy time.

Image source, PA Media

Former Conservative Party chairman Sir Jake Berry has said "machismo and chest beating" do not work when it comes to union negotiations.

Speaking on Times Radio, he reiterated his call for the government to negotiate on pay with the nursing union to avert further strikes.

"I don't regard it as controversial to say - I mean, I know others may - to say: 'Let's just try and be realistic about this'.

"There is no do-nothing option except continued strikes. And I just think the cancellation of probably literally hundreds of thousands of non-urgent appointments yesterday has huge repercussions for an already-overstretched health service."

He adds: "It is time for pragmatism and talking between the government and the unions. I don't see why that is controversial."

Speaking to the BBC earlier this morning, RMT leader Mick Lynch said there had been "an exchange of views" in government negotiations.

He added that it was important to "work quicklly" and noted that all parties were getting together and working on solutions and compromises.

A spokesperson for the Rail Delivery Group, which represents train companies, says negotiations over the rail dispute are a "painstaking process".

Dan Panes told the BBC that he still remained hopeful a resolution could be found.

"The conversations that we've been having all the way through, I have to say, with all the unions' representatives have been very constructive.

He said he believed most people recognise that the way that people use the railway has changed as passenger numbers and revenue were still down on 2019.

Panes added: "We need to make sure that colleagues across the country get a fair pay rise that is balanced by a sensible set of reforms that make sure that the railway is safeguarded for the future."

We've just head from Mick Lynch, the boss of the RMT union. It's involved in two negotiating battles, one with Network Rail, where it represents around 20,000 signallers and maintenance workers, and the other with the Rail Delivery Group, where it represents about 20,000 workers at 14 train companies.

This week, the much smaller TSSA and Unite unions said that they had accepted offers on pay on behalf of their members at Network Rail, which owns and maintains the railways across Britain.

But Mick Lynch pointed out that would have no bearing on the RMT's planned strike action.

He said that the deal that the TSSA was "not good enough" for its members who work in different roles, which he said were often more managerial jobs.

"The RMT will continue to seek a settlement for our people that are a distinct group," he told the BBC.

Members of the RMT rejected Network Rail’s latest offer because it said it would mean thousands of job losses and an increase in antisocial working hours for staff.

Prime Minister Rishi Sunak says the government remains open to talks to negotiate pay with nurses but adds that a demand for 19% pay rise by the Royal College of Nursing is unaffordable.

Speaking while on a visit to Belfast, Sunak told BBC News NI: "The health secretary has always been clear that his door is always open for talks - we want to be reasonable, we want to be constructive.

"We've got enormous gratitude for all public sector workers for the job they do and I know things are difficult right now.

"That's why the government is providing lots of support for people particularly with energy bills."

He says that's why the government accepted in full the recommendations of an independent pay body about what fair pay levels were.

Although we've heard the boss of the RMT union, Mick Lynch, suggest that disruption for passengers over the festive period would be minimal, some train companies have already been urging travellers to change their plans.

Avanti West Coast has told its customers only to travel if necessary, with its last train services on Christmas Eve wrapping up by about 13:30.

In responses to customers, it has been saying that customers with existing tickets for Christmas Eve could swap to an earlier service, or to 23 December.

Asked how much of a pay increase would be enough for RMT union members, Mick Lynch says "I don't negotiate with the BBC but we'll discuss that behind closed doors with the employers".

"We've asked for substantial increase in pay. We don't put a figure either publicly or to the employers in our claims," he says.

Lynch says it's dependent on what the government want us to do.

"The government is insisting that all this money is self generated from our own members' working practices so it depends what can be generated through the savings and efficiencies they're demanding."

"It's not as complex as me saying 'I'd like this amount of money' and them saying we'll see what we can do, unfortunately it's very complex."

In response to promises by rail bosses that safety will not be compromised, RMT's Mick Lynch says proposed measures will compromise its staff safety.

"At the moment we have planned preventative maintenance which ensures we have a safe regime. They're going to move to risk based maintenance which means 50% of the current level of inspections and maintenance work will be cut," Lynch tells the BBC.

"So there'll be half the work getting done compared to previously and we believe that compromises safety."

He says the measures they want to bring in regarding staff skills such as "how they're deployed and the constant level of night work will be unhealthy and have a detrimental effect on their wellbeing."

Mick Lynch has been giving more detail on how negotiations with bosses and meetings with the rail minister have been going.

Speaking to the BBC News Channel, he said that there had been "an exchange of views" but it was important that all parties were getting together and working on "solutions".

He added that he'd like to put some improved proposals on pay and working conditions to its members in the RMT union to get things solved.

But the key thing? "We need to work quickly, and we need a bit of goodwill from all parties."

Image source, Getty Images

As we've been reporting, the Transport Salaried Staffs' Association (TSSA) has reached a deal with Network Rail to accept its latest pay offer.

Chris Rylah, the TSSA organiser for Network Rail, says the deal has taken "months and months of very hard and long negotiations," including having to take strike action.

He says the TSSA didn't put a figure on its pay claim to Network Rail 12 months ago, but asked for a "decent pay rise" to reflect the cost of living and a job security package to give its members "peace of mind to know they'll actually have a job in the new year".

"It wouldn't have happened without the collective action of our members willing to lose pay and go on strike to get there."

He says the government is "holding back" its members who work in the train companies.

"The present offer is nowhere near what Network Rail have offered and that's where the government is getting in the way of sorting this dispute across the whole of the rail industry."

We've just heard from the general secretary Mick Lynch on Sky News about what people might be able to expect if they are travelling for Christmas.

He suggested that disruption between 24 and 27 December would be "minimal".

"We know that the public will be upset and even angry about the disruption. Some of that anger should be put towards the Government and the companies, we believe," he said.

"The railway shuts down on Christmas Eve in any case to do engineering works, so there aren't scheduled trains on Christmas Day, nor on Boxing Day, and the railway curtails its activities early on Christmas Eve," he pointed out.

Because of strike action this year, that will be a little earlier than usual.

"But people have got time now to make plans," he said, adding that he hopes to "progress" talks with rail companies to try find a resolution in the next week or so.

Image source, PA Media

A commuter at King’s Cross Station in London has said it's “really sad” that members of the Rail, Maritime and Transport union are striking at Christmas time.

Heather Smith, 66, said she's lucky that her train is still running but said the strikes are impacting people trying to get home to their families for Christmas.

“I have sympathy with most railway workers except perhaps the train drivers because the train drivers are on very good salaries, they have good working conditions," she said.

“Sadly these guys, the union’s bringing them out on strike but they don’t get paid and their families must be struggling.”

Image source, Leon Neal

Strikes have been disrupting everything from train services to postal deliveries and teaching in schools.

More workers are expected to take industrial action, as demands grow for better working conditions and pay increases to keep up with rising prices.

Ambulance workers, nurses, rail workers, bus drivers and baggage handlers have all announced industrial action this winter.

Around 1,000 Border Force staff are also expected to walk out on eight days between 23 December and New Year's Eve.

Driving examiners are holding rolling strikes until 16 January and Royal Mail workers are striking on days up to 24 December.

And earlier this month, members of the Scottish Secondary Teachers' Association (SSTA) and the NASUWT took strike action.

In November, tens of thousands of staff at 150 UK universities walked out on three days over pay.

Read more here.

Matt Taylor
BBC Weather

Image source, PA Media

Away from the snow, it’s been another bitterly cold night. Here were some of the coldest spots …

Loch Glascarnoch -13.5C

Braemar -13.0C

Benson -11.5C

Kinbrace -11.4C

Dalwhinnie & Balmoral -11.3C

BUT, the coming nights won’t be quite as cold

Find the latest forecast where you are here.

Image source, Press Association

Travellers relying on the rail network are facing another day of disruption, as members of the UK's biggest rail union the RMT hold a walk out for 48 hours until the end of Saturday, hitting services throughout England, Scotland and Wales.

One delayed commuter at King’s Cross station in London has said that public support is “waning” for striking members of the Rail, Maritime and Transport union (RMT).

Mark Ruston, 43, who works in a bank, said: “It’s a bit annoying having to wait now, my train’s now delayed, it’s frustrating.

“I’m not sure it’s working for them (RMT), I think the faith that people had in them is kind of waning really, isn’t it?

He said he understands why people are striking but thinks "it doesn’t really make any difference... no one really cares that much except for the commuters.”

Image source, PA Media

Members of the Transport Salaried Staffs Association (TSSA) have "voted overwhelmingly" to accept to the latest pay offer made by Network Rail.

The TSSA - which represents 2,500 rail controllers, operators, station and admin staff - have been striking over pay, job security and conditions and is still in dispute with other rail operating companies.

Chris Rylah, TSSA organiser for Network Rail who has been part of negotiations, said "it's not perfect but we believe it's a fair deal which is why our members voted overwhelmingly by 85% to accept," he tells BBC Radio 4's Today Programme.

Matt Taylor
BBC Weather

With travel already disrupted due to the rail strikes, it’s going to be even more difficult on the roads and pavements across Central Scotland this morning.

The Met Office have issued an AMBER weather warning for snow for the duration of the morning.

5cm to 10cm of snow is possible on lower ground, 20cm or more on the hills.

All the details on Weather Warnings can be found on the BBC Weather app.

Marc Ashdown
Business correspondent

Paddington is usually bustling with noise and determined London commuters. But today it is eerily quiet.

It is possible to get a train to places like Bristol, Plymouth and Cardiff, but the departures boards are sparse with about five services an hour displayed.

The few would-be passengers milling around are glued to their phones, or in conversation with a handful of volunteers from Network Rail, no doubt seeking travel advice.

A family with a buggy and two large suitcases looked distraught as they were told their train wasn’t running.

There isn’t much festive cheer for retailers either. Most are closed, those that have opened up are deserted.

One of the UK’s busiest transport hubs, at the busiest time of the year, currently resembles something of a ghost station.