The King will confront Britain’s role in the transatlantic slave trade with “unflinching honesty” and “sincere sorrow” when he speaks to Commonwealth leaders in Antigua and Barbuda next week.

But Buckingham Palace has made clear that any formal apology on behalf of the nation remains a matter for the Government, after Prime Minister Andy Burnham opened the door to making one.

Charles, who arrived in Antigua and Barbuda on October 30, following visits to the Bahamas and Guyana, will address presidents and prime ministers at the opening of the Commonwealth Heads of Government Meeting on November 3.

“As we have indicated, the King will not shy away from confronting the most shameful aspects of the past during this visit,” said a spokesman for the King.

“You may therefore expect him to address them in his speech with unflinching honesty, sincere sorrow, and respect for the wider discussions that will be taking place between relevant governments on this issue at CHOGM and beyond.

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“He will be speaking at CHOGM in his capacity as Head of the Commonwealth. It would not be appropriate for him to address matters of particular policy relating to the UK Government’s position.”

What is the UK’s position on the apology?

The comments come after the Prime Minister signalled a significant shift in the Government’s approach to issues around Britain’s colonial legacy.

Writing in the Guardian newspaper, Mr Burnham said he was prepared to consider a formal apology.

“We are offering a structured dialogue with those affected by the transatlantic slave trade,” he wrote. “Listening to calls for a formal apology on behalf of the British state will form an important part of this process and I am open to them.”

But he ruled out reparations, saying, “I do not think that British people today can be held liable for historical wrongs, however heinous, that happened in a different age under different laws and in which they played no personal part.”

The announcement raised fresh questions about what the King might say on Tuesday, particularly after Government advice before his tour was that no apology would be forthcoming.

King Charles’s delicate position on royal tour

But Palace sources have stressed that Charles was informed of the Prime Minister’s position in a timely manner and that no changes have been made to his speech or programme as a result.

It is a delicate diplomatic balancing act for the King, who is speaking as Head of Commonwealth, an organisation that includes countries which have long called for Britain to apologise and offer compensation for historic wrongdoing.

“His Majesty is well practised on the diplomatic tightrope, as you’ve seen again several times this year” said the spokesman. “He is up for challenging visits with complex issues and relationships in play. He sees it as his role to ‘bat for Britain’, the Realms and wider Commonwealth, promoting, protecting, and enhancing relationships at the highest level.

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“One of the many benefits of a Constitutional Monarchy is the ability to transcend politics.”

The King has already acknowledged the painful legacy of slavery during his trip.

At a youth rally in the Bahamas, he spoke of the “great suffering of the past” and in Guyana, he visited Independence Park in Georgetown, the execution site for 33 enslaved people involved in an attempted rebellion.

He has previously expressed his personal sorrow over slavery, speaking of his determination to deepen his understanding of its enduring impact at CHOGM in Rwanda in 2022 and again in Samoa two years later.

But calls from Caribbean leaders for Britain to go further have intensified ahead of this week’s summit.

The Palace is keen to emphasise the King’s wider role in bringing Commonwealth nations together, particularly at a time of growing global instability.

A senior Palace aide said: “In keeping with the CHOGM agenda of ‘Accelerating Partnerships and Investment for a Prosperous Commonwealth’, His Majesty’s speech will therefore primarily focus on encouraging practical solutions and united efforts to address global challenges and opportunities relevant to all 56 members of the Commonwealth family today.”

But with the British Government now prepared to consider an apology, the King’s words on slavery will be more closely scrutinised than ever.