King Charles will address the lasting pain of the transatlantic slave trade in Antigua on Tuesday, as Prime Minister Andy Burnham signals a willingness to consider a formal British apology.

Buckingham Palace said the King would confront the subject honestly and with sincere sorrow when he speaks to Commonwealth leaders on the final leg of his Caribbean tour. His address will acknowledge discussions between governments, while keeping clear of decisions on British policy.

Burnham’s openness to an apology marks a departure from the position he previously maintained under his predecessors. Britain has never formally apologised for slavery or offered reparations. His comments did not extend to considering reparation payments: an apology and financial redress remain separate questions.

The Palace is understood to have known in advance about Burnham’s comments, published on Friday night. The King has not altered his speech in response. A Palace spokesperson said it would be inappropriate for him to address the government’s policy position, while royal sources stressed that an apology was a decision for ministers.

The distinction has accompanied a tour that has repeatedly brought Britain’s colonial legacy into view. In the Bahamas, Charles acknowledged past suffering. In Guyana, he visited the site of public executions following the 1823 Demerara Slave Rebellion, in which hundreds of enslaved people were killed. The Palace described the visit as an opportunity to learn about slavery and resistance.

Other engagements have addressed the environment, opportunities for young people and trade with Britain. A royal aide described the King’s approach as representing Britain, the realms and the wider Commonwealth through difficult diplomatic relationships.

Burnham characterised the slave trade as brutal and barbaric and argued that Britain must confront its history. He also pledged to strengthen the Commonwealth. Charles regards the 56-country organisation as a means of achieving change; the Palace argues that its breadth, combined with personal relationships between leaders, supports practical co-operation.

Queen Camilla is accompanying the King in Antigua, where he arrived on Friday evening. They are due at a Sunday morning church service before joining Independence Day celebrations.

The visit follows difficult months involving his brother Andrew Mountbatten-Windsor, a book by former brother-in-law Earl Spencer, and the Duke and Duchess of Sussex’s surprise return to Britain with their two children in August. A senior aide expressed confidence in the King’s handling of family matters. The Palace would not comment publicly on serious allegations concerning Meghan’s father, Thomas Markle.

Charles continues cancer treatment following his diagnosis in early 2024, with the Palace reporting positive progress. Approaching his 78th birthday, he will have undertaken about 36 engagements during the nine-day tour in hot, humid conditions.