It's widely accepted that the late republican Freddie Scappaticci was the agent, codenamed "Stakeknife".
He headed the IRA's so-called "nutting squad", a notorious internal security unit tasked with hunting and executing informants, but was himself operating as a mole for British intelligence.
The final report of a seven-year investigation named Operation Kenova has found that "there is a compelling ethical case" to reveal the agent's identity.
Operation Kenova live: 'Stakeknife' spy inside IRA committed 'worst possible' crimes
Head of Kenova Sir Iain Livingstone said that "it is in the public interest that Stakeknife is named". He urged the government to depart from its "neither confirm nor deny" (NCND) policy on the grounds of public interest.
It's understood that the government believes Stakeknife cannot be officially named at this time due to some outstanding legal issues. Sky News has approached No 10 Downing Street for comment.
Freddie Scappaticci died two years ago denying that he was the agent, but all sides in Northern Ireland accept his denial was false.
The report also found a "significant failure" by MI5 in its late provision of materials to the investigation. "The further material revealed MI5 had earlier and greater knowledge of the agent than previously stated," the report says.
Sir Ian Livingstone added that "further investigative opportunities were undoubtedly lost", and that the confidence of the communities in Northern Ireland was undermined. Sky News has approached the security agency for comment.
Stakeknife produced a "vast" amount of intelligence. 3,517 reports from the agent were discovered, including 377 from one 18-month period. But the report found the intelligence was not shared with those who could have used it to save lives.
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Last year, Operation Kenova's interim report found the security forces were frequently aware of imminent abductions and murders but failed to protect those at risk.
Today's report found his army handlers even took Stakeknife out of Northern Ireland for two holidays, at a time when he was sought by police for murder and kidnapping. He was flown on military aircraft and given military ID.
As a result, preventable deaths occurred with the security forces' knowledge and those responsible were not brought to justice and were instead left free to reoffend.
'Wholly unjustified criminality'
The 2024 report also concluded that Stakeknife was involved in "very serious and wholly unjustifiable criminality", including murder, and claims his intelligence saved "countless" or "hundreds" of lives were exaggerated. It found that the number of lives saved by his spying ranged from the high single figures to low double figures.
This contradicted claims that Scappaticci had saved hundreds of lives during the years he was active, with a former defence chief describing him as "the goose that laid the golden eggs". The interim report found that claim to be "inherently implausible" and "a comparison rooted in fables and fairy tales".
The 2024 report also called on the UK government to apologise to bereaved families, given that many murders were avoidable.
'Each evil act being the epitome of cowardice'
There was also a call for an apology from republican leaders for "the most shameful and evil" actions of the Provisional IRA (PIRA). "It was PIRA that committed the brutal acts of torture and murder, each evil act being the epitome of cowardice," the report stated.
No prosecutions connected with Stakeknife will take place, prosecutors in Northern Ireland have already decided.
Families of IRA victims associated with Stakeknife will give their response to the Kenova report in a news conference later today.
They want Scappaticci to be officially named, and many are seeking an apology from the British government.
At the end of the 45-minute interview with Politico, EU leaders might be forgiven for thinking, with friends like these, who needs enemies?
"Europe doesn't know what to do," Trump said, "They want to be politically correct, and it makes them weak."
On the contrary, I would imagine some choice words were being uttered in European capitals as they waded through the string of insults.
First up, the US president criticised European leaders for failing to end the war between Russia and Ukraine.
"They talk but they don't produce. And the war just keeps going on and on," he said.
The fact that the Russians have shown no real commitment to stopping the invasion they started is not mentioned.
Instead, the blame is laid squarely at the feet of Ukraine and its allies in Europe.
"I think if I weren't president, we would have had World War III," Trump suggested, while concluding that Moscow is in the stronger position.
Critics claim that the White House has emboldened the Kremlin and brought Putin in from the cold with a summit and photo opportunities.
Trump highlights the fact that his return to office forced many European NATO members to increase defence spending drastically.
On this, he is correct - the growing insecurity around how long America can be relied on has brought security into sharp focus.
The release of the new US national security strategy has only added to the feelings of unease.
German Chancellor Friedrich Merz on Tuesday claimed some of its contents were unacceptable from a European point of view.
"I see no need for America to want to save democracy in Europe. If it was necessary to save it, we would manage it on our own," he told a news conference in Rhineland-Palatinate, the German state where Trump's paternal grandfather was born.
The leader of the EU's biggest power also said that the new US strategy was not a surprise and largely chimed with the vice president's speech at the Munich Security Conference in February.
For this reason, Merz reiterated that Europe and Germany must become more independent from America for their security policies.
However, he noted, "I say in my discussions with the Americans, 'America first' is fine, but America alone cannot be in your interests."
For his part, while Trump said he liked most of Europe's current leaders, he warned they were "destroying" their countries with their migration policies.
He said: "Europe is a different place, and if it keeps going the way it's going, Europe will not be…in my opinion, many of those countries will not be viable countries any longer. Their immigration policy is a disaster".
He added: "Most European nations... they're decaying."
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Again, the comments echoed his security strategy, which warned immigration risked "civilisation erasure" in Europe.
There's no doubt immigration is a major concern for many of the continent's leaders and voters.
However, irregular crossings into the EU fell 22% in the first 10 months of 2025 according to Frontex, a fact which seems to have passed the president and his team by.
"Within a few decades at the latest, certain Nato members will become majority non-European", his security document warned.
It also suggested "cultivating resistance" in Europe "to restore former greatness" leading to speculation about how America might intervene in European politics.
Trump appeared to add further clarification on Tuesday, saying while he did not "want to run Europe", he would consider "endorsing" his preferred candidates in future elections.
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This comment will also ruffle feathers on the continent where the European Council President has already warned Trump's administration against interfering in Europe's affairs.
"Allies do not threaten to interfere in the domestic political choices of their allies," Antonio Costa said on Monday.
"The US cannot replace Europe in what its vision is of free expression… Europe must be sovereign."
So, what will happen now, and how will Europe's leaders respond?
If you are hoping for a showdown, you will likely be disappointed.
Like him or loathe him, Europe's leaders need Trump.
They need the might of America and want to try to secure continued support for Ukraine.
While the next few days will be filled with politely scripted statements or rejections of the president's comments, most of his allies know on this occasion they are probably best to grin and bear it.
The bodies of a man, 35, a woman, 55, and another person, about whom no information was given, were recovered after a major rescue operation using jet skis and helicopters on Sunday.
A woman, the fourth victim, died on Monday, a day after she had been revived at the scene and airlifted to hospital.
The victims have not yet been named.
The pool is located at Isla Cangrejo, on Tenerife's Los Gigantes coast, and is popular with foreign holidaymakers.
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It is bordered by volcanic rock on one side and cemented off from the sea on the other.
But it can be very dangerous during rough seas when large waves can easily overcome the cement barrier.
'We ask people to pay attention'
A weather advisory for rough seas was in effect at the time the swimmers were swept away, local media reports.
One outlet had reported that the pool had been closed to swimmers since 3 December.
Emilio Navarro, the mayor of Santiago Del Tiede, said: "We ask people to pay attention to the signage put up by the authorities. It's to take care of and protect everyone."
Last month, three people were killed and 15 injured in Tenerife after a tidal surge during treacherous weather.
The Glaswegian, 59, took home the visual arts prize along with £25,000 at an award ceremony on Tuesday in Bradford, this year's UK City of Culture.
As reported by The Guardian, she is the first artist with a learning disability to win the award.
Along with Hanging Sculpture 1-10, which European art exhibitors Manifesta commissioned her to create at a disused power station in Barcelona, Ms Kalu won for her presentation in Conversations, a group exhibition at Walker Art Gallery in Liverpool.
For the sculpture series, the artist created the vividly-coloured works from repeated lines and wrappings of different materials, making nest or cocoon-like forms.
The installation consisted of 10 large brightly-coloured sculptures that hung from grey concrete pillars of the industrial site.
Meanwhile, for Conversations, Kalu presented work in pen, graphite and chalk pen on two pieces of paper.
The jury, which was chaired by Alex Farquharson, the director of Tate Britain, commended Kalu's "bold and compelling work" and praised the "lively translation of expressive gesture" in the abstract sculpture and drawing.
The panel also acknowledged her scale, composition and colour, highlighting "the powerful presence" her works have.
Kalu is also a resident artist at ActionSpace's studio, which supports learning disabled artists across London at Studio Voltaire, and beat out fellow shortlisted artists Rene Matic, Mohammed Sami and Zadie Xa.
The works by the four artists are currently available to see at a free exhibition at Bradford's Cartwright Hall Art Gallery until 22 February.
Named after British painter JMW Turner, this year's prize marked the 250th anniversary of his birth.
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Previous winners include artist Damien Hirst in 1995 and filmmaker Sir Steve McQueen in 1999, while last year's winner, Jasleen Kaur, picked up the prize for Alter Altar - which covered a red sports car with a giant ornamental doily mat.
He died on Tuesday following a "tragic accident" while watching the Ukrainian military test a new weapon away from the frontline, the Ministry of Defence (MoD) said.
Hostile fire is not thought to have been involved.
The Sun newspaper reported that the serviceman was in the Special Forces. An MoD spokesperson would neither confirm nor deny the claim and the individual's rank and service have not yet been revealed.
Prime Minister Sir Keir Starmer and Defence Secretary John Healey paid tribute to him.
"My deepest sympathy and condolences to the family of the member of our Armed Forces who sadly lost their life today," Sir Keir said.
"Their service and sacrifice will never be forgotten.
Mr Healey said he was "devastated by the death of a UK service person in Ukraine.
"My thoughts are with their family, friends and colleagues as they grieve for a loved one. Our hearts go out to them."
The UK has previously acknowledged the presence of a small number of service personnel in Ukraine who are helping the Ukrainian military, as well as providing security for the British ambassador and other diplomats at the embassy in Kyiv.
There are also British troops who have been giving medical training.
Dozens of former British troops, as well as foreign fighters from many other countries, have travelled to Ukraine to fight for the Ukrainian armed forces ever since Russia launched its full-scale war almost four years ago.
A number of them have been killed in battle.
But this is the first time a serving member of the military has died.
"It is with deep regret that we must announce that a member of the UK Armed Forces died in Ukraine this morning, Tuesday 9 December," the MoD said in a statement.
"He was injured in a tragic accident whilst observing Ukrainian forces test a new defensive capability, away from the front lines."
It was not immediately clear whether the accident happened on the same day that he died. The location where it occurred has also not been confirmed.
The serviceman's family has been notified.
Shines a light on UK military's role
The death shines a rare light on the little-discussed work of the UK military inside the country.
Very little is said about the mission amid concerns that Russia could exploit the discrete UK presence to falsely claim that serving British soldiers are actively fighting against Russian troops.
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The first confirmed death of a serving member of the British armed forces confirms the significant risks they are taking.
But the Kremlin will also likely seize on the tragedy to amplify bogus claims about NATO forces already being deployed in Ukraine, fighting directly against Russia.