The palace said the King personally called both Harry and the Prince of Wales – as well as his siblings the Princess Royal, the Duke of York and the Duke of Edinburgh – to share news of his health.
Heir to the throne Prince William is understood to be in regular contact with his father.
The monarch has begun a schedule of regular treatments and is said to be receiving expert medical care from a specialist team.
But he has been advised by doctors to postpone his public-facing duties.
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5:21
‘Serious statement from Palace’
The King travelled from Sandringham in Norfolk to London this morning to start treatment as an outpatient. He is at home in London this evening, most likely in Clarence House.
He will carry on working behind the scenes on his red boxes – his state business and official papers.
A palace spokesperson said: “His Majesty has been treated for benign prostate enlargement.
“It was during this intervention that the separate issue of concern was noted and subsequently diagnosed as a form of cancer.
“This second condition will now receive appropriate treatment.”
The head of state underwent a procedure for an enlarged prostate, spending three nights in hospital in late January.
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A statement from Buckingham Palace said today: “During the King’s recent hospital procedure for benign prostate enlargement, a separate issue of concern was noted. Subsequent diagnostic tests have identified a form of cancer.
“His Majesty has today commenced a schedule of regular treatments, during which time he has been advised by doctors to postpone public-facing duties.
“The King is grateful to his medical team for their swift intervention, which was made possible thanks to his recent hospital procedure.”
A new level of openness about royal medical matters
The King looked well as he walked to church at Sandringham on Sunday which makes this announcement even more unexpected.
The palace is keen to stress he remains wholly positive about his treatment but inevitably aware that his diagnosis will cause concern.
It feels like a complete change from what we would expect from the Royal Family with a new level of openness about their medical matters.
With the Queen and Prince Philip, the amount of detail was always much more scarce.
So why the change of tack?
There is an acknowledgment that as our head of state we should know about something this serious.
But it’s clear the palace and the monarch wanted to make sure they were in control, as much possible, when it came to revealing his cancer diagnosis to the world.
A kind of deal has been done. We’ve let you in on what’s going on, now it’s time to give the King time away from the cameras for this period of treatment and recovery.
Monarch ‘remains wholly positive’
The palace said His Majesty “remains wholly positive about his treatment” and “looks forward to returning to full public duty as soon as possible”.
The statement added that the King had chosen to “share his diagnosis to prevent speculation” and “in the hope it may assist public understanding for all those around the world who are affected by cancer”.
News of the King’s diagnosis comes as his daughter-in-law Kate, Princess of Wales, recovers from abdominal surgery following a hospital stay of around two weeks.
Reaction to King’s diagnosis
The King is heading into his cancer treatment as a “very fit 75-year-old” who has always been “very energetic and determined”, said Sky’s royal commentator Alastair Bruce.
“Everybody knows the impact of the word cancer,” he said, adding the monarch’s diagnosis gives it “something of a focus”.
“I think that having come down to London, we hear, to start this procedure – we know he does so with enormous enthusiasm,” he said.
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1:38
What next for the King?
The King has “thrown himself” into his role of head of state and may be “bringing light” to the issue incidentally through his own diagnosis, Bruce continued.
Prime Minister Rishi Sunak reacted to the news of the King’s cancer diagnosis by writing on X: “Wishing His Majesty a full and speedy recovery.
“I have no doubt he’ll be back to full strength in no time and I know the whole country will be wishing him well.”
Labour leader Sir Keir Starmer also issued a get well message to the head of state.
An emergency measure has been triggered by the Ministry of Justice to deal with prison overcrowding in England.
Operation Early Dawn will see defendants in police custody remain there – and not be transferred to magistrates’ courts for bail hearings – in case there is no space in jail cells for that prisoner if they are remanded into custody.
Sky News understands the measure is just being used in London and the North East, at the moment.
The Law Society, which represents solicitors in England and Wales, says many magistrates’ court cases will be delayed as a result, with the most serious cases given priority.
Defendants who are not prioritised will be released on police bail, the Law Society added.
At Prime Minister’s Questions, Sir Keir said the “prison system is in chaos” and asked the prime minister if his decision to “let prisoners out 70 days early makes our country more secure”.
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A Ministry of Justice spokesman said: “This government is categorical that the most dangerous offenders should stay behind bars for longer, which is why new laws will keep rapists locked up for every day of their prison sentence and ensure life means life for the most horrific murderers.
“We continue to see pressure on our prisons following the impact of the pandemic and barristers’ strike which is why we have initiated a previously used measure to securely transfer prisoners between courts and custody and ensure there is always a custody cell available should they be remanded.”
The Law Society said it was “crystal clear” the prison space crisis “is a consequence of the government’s approach to justice including over a decade of underfunding of our criminal justice system”.
A spokesman added: “Victims, witnesses, defendants and lawyers will today turn up at magistrates’ courts across England only to find out that their cases have been delayed due to a crisis in prison and police cell capacity outside of their control.
“As of now, we understand that this pattern will be repeated every day that this emergency measure is in place.”
High-risk offenders being released early
In February, a separate scheme – the End of Custody Supervised Licence (ECSL) – to allow prisoners to be released early due to a lack of space was extended indefinitely. Those convicted of serious offences are not eligible for early release.
A row broke out over the scheme during Prime Minister’s Questions on Wednesday after Labour leader Sir Keir Starmer accused Rishi Sunak of allowing sex offenders to be released early.
“He was a risk to children and subject to an exclusion zone that included the local authority responsible for trying to house him,” the report said.
But the prime minister said: “As I’ve said, no one should be put on this scheme if they are a threat to the country.
“And let me be crystal clear… it does not apply to anyone serving a life sentence.
“Anyone convicted of a serious violent offence, anyone convicted of terrorism, anyone convicted of a sex offence, and crucially, in contrast to the system that Labour had put in place, governors and the prison service have an absolute lock so that no one is put on this scheme who shouldn’t be.”
The owner of Royal Mail has said it is “minded” to accept a revised takeover bid by Czech billionaire Daniel Kretinsky.
The latest offer from Mr Kretinsky’s investment firm EP Group values the Royal Mail parent company International Distribution Services (IDS) at £3.5bn.
An extra shareholder pay out of 8 pence a share has been offered by EP Group, if the deal closes, as has a 2 pence per share payment to every stakeholder, expected to be paid in September.
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It would bring the total value of an IDS share to 73% more than it cost before the prospect of a buyout was raised.
‘Good value’
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“Having considered the proposal, the board has indicated to EP Group that it would be minded to recommend an offer to IDS shareholders”, the IDS board said.
The price is “fair” and reflects the value of current growth plans, the IDS chairman said.
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2:23
Royal Mail could be allowed to deliver letters just three days per week, under a series of options outlined by the industry regulator.
Consideration was given by the board to the national significance of Royal Mail as the operator of the postal network.
“The board is particularly mindful of Royal Mail’s unique heritage and responsibilities as the designated universal service provider in the United Kingdom and a key part of national infrastructure”, it said.
In assessing the proposal, the board has also been very mindful of the impact on Royal Mail and GLS and their respective stakeholders and employees, as well as broader public interest factors”.
EP Group has until 29 May to advance or withdraw its takeover bid.
Who isDaniel Kretinsky?
There has already been scrutiny of Mr Kretinsky’s part ownership in the postal company but a government national security concerns review into his investment led to no intervention.
He also owns parts of West Ham Football Club and Sainsbury’s.
EP Group, which he controls, has financial interests in energy, logistics, and food retail.
The King and Queen have arrived at St Paul’s Cathedral in central London for a service of dedication for the Order of the British Empire.
Established by King George V in 1917 to reward outstanding contributions to the war effort – it now recognises the work of people from all walks of life.
Around 2,000 people who are holders of the royal honours such as MBEs and OBEs – from the UK and Commonwealth – formed part of the congregation.
The King is the Sovereign of the Order of the British Empire, and the Queen is the Grand Master of the Order of the British Empire.
It comes after the King carried out his first investiture in five months – and his first since his cancer diagnosis – at Windsor Castle yesterday.
Archbishop of Canterbury Justin Welby, who conducted the service for the coronation, was one of the 52 recipients of an investiture – and was given the Knight Grand Cross of the Royal Victorian Order.
Awards of the Royal Victorian Order are in the King’s gift and are bestowed independently of Downing Street to people who have served the monarch or the Royal Family in a personal way.
He said the King seemed in “very good spirits indeed” and was “looking very well” as they spoke during the ceremony.
The monarch, who is receiving treatment for an undisclosed form of cancer, was given permission by his doctors to return to public duties last month.
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Dean of Westminster Abbey Dr David Hoyle was among the other people honoured at the ceremony, as he was made a Knight Commander for his own role in the coronation.
He revealed there were plans for a building in the King’s honour to be built on the side of Westminster Abbey.
“We have already done the archaeology, so the site is prepared. We have plans which the King has seen. We hope we might have it built in the next two to three years,” he said.