Should that happen, General Sir Gwyn Jenkins said it would be the first time since the end of the Second World War that Britain's warships and submarines were not the dominant force in their most vital sea lanes alongside their allies.

"We are holding on, but not by much," he told a conference in London on Monday.

"There is no room for complacency. Our would-be opponents are investing billions. We have to step up, or we will lose that advantage."

As a senior, serving military officer speaking publicly, he did not make any direct criticism of the speed of plans by Sir Keir Starmer's government to increase defence spending.

But Sky News has reported that he and his fellow chiefs held a "very difficult meeting" last month over how to fund plans to rebuild the armed forces amid fears of further cuts.

Defence sources said there was growing concern at the very top of the armed forces about a gap between the promises being made by the prime minister to fix the UK's hollowed-out defences and the reality of the size of the defence budget, which is currently not seen as growing fast enough.

That means either billions of additional pounds must be found more quickly, or ambitions to modernise and transform the armed forces might need to be curbed, despite warnings of mounting threats from Russia and China, and pressure from Donald Trump on allies to spend more on their own defences.

A Sky News and Tortoise podcast series called The Wargame tracks the hollowing out of the UK's military since the end of the Cold War and the risk that has created.

👉Search for The Wargame on your podcast app👈

General Jenkins, the first Royal Marine to serve as First Sea Lord, used a speech at the Sea Power Conference to say that Russia is still investing billions in its naval capabilities - in particular the Northern Fleet that operates in the Atlantic - even as it wages war against Ukraine.

There has been a 30% increase in Russian incursions in the North Atlantic in the past two years, he said.

That included the Yantar spy ship, which last month was spotted off the coast of Scotland and even shone a laser at the pilots of a Royal Air Force reconnaissance plane that was tracking the vessel.

Yet General Jenkins said what Russia is doing beneath the surface of the waves, where the UK and its allies store vital communications cables as well as critical oil and gas pipelines, was even more concerning.

"I can also tell you today that the advantage that we have enjoyed in the Atlantic since the end of the Second World War is at risk," he said.

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Navy facing huge challenges

It is a particularly tough time for the navy, which has more ships and submarines alongside and unable to operate than at sea or at least ready to sail.

The service is also suffering from a shortage of sailors and in particular submariners, which again is impacting the availability of the fleet.

The crisis follows decades of funding cuts since the end of the Cold War, compounded by a litany of botched procurement programmes that has all too often seen vessels coming into service years late, at an inflated price and in too few numbers.

Vision of 'hybrid navy'

Despite the sombre tone, the First Sea Lord set out how he wants to transform his service and make it ready to fight a war - though not until 2029, a timeline that could be too slow if some predictions about the threat posed by Russia to NATO are correct.

His vision - working with industry and other allies - is about developing a blend of manned ships and submarines as well as unmanned ones - a "hybrid navy".

He is also stripping back what he called the navy's own bureaucracies to enable the service to move much faster - crucially at the pace of the threat and the pace of rapid and growing technological change.

"We will face headwinds, we will face rough seas, but together, we can solve these problems if we have the appetite, if we have the determination, and if we have the mindset."

Earlier, the prime minister met with Ukrainian President Volodymyr Zelenskyy, French President Emmanuel Macron and German Chancellor Friedrich Merz at Downing Street for crisis talks on the future of Ukraine.

After the Downing Street meeting, a spokesperson said Sir Keir "convened a call with other European allies alongside President Zelenskyy".

"The leaders all agreed that now is a critical moment and that we must continue to ramp up support to Ukraine and economic pressure on Putin to bring an end to this barbaric war."

Ukraine latest: 'Critical stage' in push for peace

During the earlier meeting, the Downing Street spokesperson said that the leaders "discussed the importance of the US-led peace talks for European security and supported the progress made".

All four "underscored the need for a just and lasting peace in Ukraine, which includes robust security guarantees," the spokesperson added.

"The leaders agreed that, while diplomatic efforts continue, Europe must stand with Ukraine, strengthening its ability to defend against relentless attacks that have left thousands without heat or light," they said.

"They also discussed positive progress made to use immobilised Russian sovereign assets to support Ukraine's reconstruction."

After arriving in the UK, Mr Zelenskyy said in a post on Telegram that "we are joining our efforts to end this war with a decent peace for Ukraine" and that "security must be guaranteed".

He later said: "We can't manage without Americans, we can't manage without Europe and that is why we need to make some important decisions."

The discussions come as US President Donald Trump accused Mr Zelenskyy of having failed to read the latest peace plan.

He said he was "a little disappointed" in the Ukrainian leader, while insisting Russia's Vladimir Putin was "fine with it".

Mr Trump's eldest son had earlier told Sky's lead world news presenter Yalda Hakim in an interview that his father may walk away from the Ukraine peace process.

When asked directly if he believed the US president would walk away from Ukraine, he answered: "I think he may, what's good about my father and what's unique about my father is you don't know what he's going to do. He's unpredictable."

Sir Keir had earlier insisted any ceasefire must be "just" and "lasting", adding: "We are at a critical stage in the push for peace.

"The principles remain the same. We stand with Ukraine, and if there is to be a ceasefire, it needs to be a just and lasting ceasefire."

Mr Macron had insisted Ukraine's allies have "a lot of cards" - but the main issue was to "finalise these peace negotiations" and find the "best possible conditions for Ukraine, for the Europeans, and for collective security".

Moments after arriving at Downing Street, Mr Merz said he was "sceptical about some of the details in documents coming from the US" but that was one of the reasons for Monday's talks.

The four European leaders emerged from Downing Street at around 2.20pm for a group photo - but declined to answer any questions from the media.

Sir Keir and Mr Zelenskyy then went back inside the prime minister's residence for further talks while Mr Macron and Mr Merz departed.

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The London meeting comes after Mr Zelenskyy's officials concluded three days of talks with US diplomats.

Over the weekend, Mr Zelenskyy said he had discussed "next steps" with Mr Trump's advisers and was "determined to keep working in good faith".

According to Vatican sources, the Ukrainian president will next meet with Pope Leo at Castel Gandolfo, the papal residence outside of Rome, on Tuesday morning.

Train services already in public ownership will begin to adopt a Union flag-inspired design from this spring, Heidi Alexander has confirmed.

It's part of the government's efforts to nationalise most passenger rail services in the UK and run them under the new Great British Railways (GBR) brand - with its logo to be unveiled later today.

Ms Alexander will be speaking more about GBR - which is due to be formally established in 2027 - on Mornings With Ridge And Frost from around 7.10am.

Haven't I seen this somewhere before?

The branding features the familiar double arrow symbol used by British Rail when the country's trains were last state-owned.

A spokesperson for the Department for Transport (DfT) said the "iconic" symbol has been incorporated into the new GBR logo to reflect "Britain's proud railway heritage".

Ms Alexander has insisted it "isn't just a paint job", saying: "It represents a new railway, casting off the frustrations of the past and focused entirely on delivering a proper public service for passengers."

Special one-day public exhibition launched

People in the capital will be able to see the new train livery for themselves today, with a special one-day exhibit being held at London Bridge station, where a GBR-branded Hornby model train will be on display.

The government has also partnered with a gaming company to create mock-ups of the new design, and those at the station will be able to see a digital demonstration of the new artwork in Train Sim World 6.

The new designs will also be beamed on to digital display boards over the coming days at Manchester Piccadilly, Birmingham New Street, Glasgow Central, and Leeds City.

It comes as MPs prepare to debate the government's Railways Bill in the Commons.

The government has taken control of seven major operators so far, but has pledged to return all passenger services to public ownership as contracts with existing operators expire or are broken through a failure to deliver.

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What will nationalisation actually involve?

The government has said its Railways Bill will bring 17 different organisations together and will also lead to greater accountability, better services and an easier way to buy tickets.

Among the measures is the creation of a GBR app, where passengers will be able to check train times and buy tickets without booking fees, while those with disabilities will be able to also request assistance.

The draft law would also beef up accountability by creating a strengthened Passenger Watchdog, while GBR would operate both services and maintain the railways themselves.

Ministers have pointed to improvements to existing services since they have been nationalised, such as South Western Railway boosting capacity by almost 10% by quadrupling its number of Arterio trains in service.

A new East Coast Main Line timetable will also come into effect this month, which the government says will lead to 10,000 extra LNER services every year, or roughly 60,000 extra seats a week.

The former deputy prime minister delighted Labour backbenchers with a powerful Commons speech defending her workers' rights legislation on Monday evening.

With the House of Lords locked in a battle of parliamentary "ping pong" with MPs, she told ministers: "Now is not the time to blink or buckle."

Her very public intervention came amid claims that her next move has the Labour Party on tenterhooks and that she's the favourite to succeed Sir Keir if she wants the job.

And her speech, delivered from notes and clearly meticulously prepared, appeared to send a message to Labour MPs: I'm here to make a comeback.

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The government's flagship Employment Rights Bill was championed by Ms Rayner when she was deputy PM, in the face of bitter opposition from the Conservatives.

In a bid to end the deadlock with the Lords, ministers have backed down on unfair dismissal protection from day one, proposing a compromise of six months.

Backing the compromise, brokered with the TUC, Ms Rayner said: "I know ministers had faced difficult decisions and difficult discussions with the employers and worker representatives.

"But I strongly believe that the work that has been done has been necessary, and we should be able to move forward now."

'No excuses'

Attacking the upper chamber for delaying the legislation, she said: "There is now no more time to waste.

"Vested interests worked with the Tories and the Lib Dems and, cheered on by Reform and backed by the Greens, to resist the manifesto on which we were elected.

"And now there can be no excuses. We have a mandate for a new deal for working people, and we must, and we will deliver it.

And she concluded: "It has been a battle to pass this bill, but progress is always a struggle that we fought for. Its passage will be a historic achievement for this Labour government.

"It will benefit working people now and into the future. Now is not the time to blink or buckle. Let's not waste a minute more. It's time to deliver."

Could she replace her old boss?

It was the sort of fighting talk and defiance of the government's opponents that will have cheered up Labour MPs and boosted her hopes of a comeback and even a leadership bid.

Speculation over Sir Keir's future grows more frenzied by the day, with claims that even some of his own supporters have begun the hunt for his successor.

The thinktank that ran his leadership campaign in 2020, Labour Together, is reported to be canvassing party members on candidates to replace him.

There was even a claim last week that allies of Wes Streeting were sounding out Labour MPs about a pact with Ms Rayner and a joint ticket for the leadership.

The health secretary dismissed that claim as a "silly season story", while a Rayner ally said: "There's no vacancy and there's no pact". They added that she will not "be played like a pawn".

Mr Streeting did, however, start speculation himself when he said in his Labour conference speech: "We want her back. We need her back."

Fuelling more speculation, Sir Keir went further than he had previously on Sunday, when he was asked in an Observer interview if he missed her and replied: "Yes, of course I do. I was really sad that we lost her."

And asked if she would return to the cabinet, the prime minister said: "Yes. She's hugely talented."

Sir Keir also described Ms Rayner, who left school at 16 without any qualifications, as "the best social mobility story this country has ever seen".

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But a swift return to the cabinet would be hugely controversial, because the PM's ethic adviser, Sir Laurie Magner, ruled that she breached the ministerial code by underpaying stamp duty when she bought a flat.

But she has been linked to speculation about possible efforts to remove Sir Keir if - as predicted - Labour performs badly in the Scottish, Welsh and local elections next May.

Her supporters also claim she will eventually be cleared by HMRC over her stamp duty breach, clearing the way for her to come back.

And her latest speech - combative, defiant and yet loyal - will have boosted her hopes, and reminded Labour MPs what they've missed since she quit in September.

Jan Jahanzeb and Israr Niazal, both 17, led the "highly-distressed" victim away from friends near Leamington town centre to a secluded "den-type" area in parkland, where they pushed her to the ground and attacked her.

Sentencing the pair at Warwick Crown Court on Monday, Judge Sylvia de Bertodano said they ignored the victim's "vigorous protests" and told them what they did "changed her life forever".

"No child should have to suffer the ordeal that she suffered. It's clear from the footage we have seen that no one can seriously entertain the thought that you believed she was consenting," she said.

"You both knew perfectly well that what you were doing was criminal and wrong," the judge added.

'Highly distressing'

After lifting reporting restrictions protecting the identities of the defendants, the judge told them they had "betrayed" those who come to Britain seeking sanctuary and who observed the law.

Both defendants were unaccompanied child asylum seekers who arrived in the UK last year, prosecutor Shawn Williams said.

The incident happened in May of this year.

"Highly distressing" phone video found by police showed the victim screamed for help, but Jahanzeb placed his hand over her mouth.

CCTV footage showed that after being led away against her will, the terrified victim was "moved to a bushy den-type area - a really secluded location" before, according to her, she was "pushed to her knees before being raped".

"The prosecution case is that it was probably Jahanzeb that did that, but what is certain is that Israr Niazal was present and participating," Mr Williams said.

The victim had made "explicit verbal protests" during what Mr Williams described as an abduction.

What are their sentences?

Jahanzeb, who has already been served with deportation notification papers, was given 10 years, eight months' youth detention.

Niazal, who may also be deported, was sentenced to nine years and 10 months.

They will start their sentences in a young offenders' institution and move to prison at a later date, police said.

Both pleaded guilty to rape at an earlier hearing.

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Detective Chief Inspector Richard Hobbs said the offenders "went out of their way to befriend the victim with the intention of raping her".

"The length of their sentence reflects the severity of their crime and the need to protect the public from them," he added.

After sentence was passed, Judge de Bertodano said the victim had been "beyond brave" in attending court at a previous stage, when the defendants had intended to plead not guilty.

They were both ordered to register as sex offenders.