King Charles has described the transatlantic slave trade as a "shameful chapter of history" that filled him with "profound sorrow," opening a summit of Commonwealth leaders in the Caribbean with words that were heavy on contrition and notably light on the formal apology some had requested ahead of the Commonwealth Heads of Government Meeting (Chogm) in Antigua and Barbuda.

The King said the trade in enslaved persons "still casts a shadow" over the association of nations. "The transatlantic trade in enslaved persons still casts a shadow over these islands and other members of our Commonwealth," he told the summit. "As I have said before, that shameful chapter of history is one that fills my heart with horror and my soul with the most profound personal sorrow."

There was no direct apology in the address, despite calls from some for the UK to formally apologize for its historic role in the slave trade. There was, however, an acknowledgement that the King had personally learnt more about the legacy of the trade. "The more I have furthered my own understanding of the issues, through listening, learning and looking, the more committed I have become to finding ways for us to work in modern partnership to address the wrongs of the past with action for the future," he said.

The King also offered a brief philosophy seminar on the nature of inheritance: "History is not ours to choose or to change. It is bequeathed to us in complex synthesis by forebears we can never know. Our inheritance includes both their achievements and their failures - the good they did as well as the wrongs."

Prime Minister Andy Burnham, also at the summit, has said he is open to Britain issuing a formal apology but has ruled out financial reparations. Speaking on Tuesday, he said his government was bringing a new approach aimed at "revitalise the Commonwealth," despite turning down demands for reparations. "I've been very clear that we do not support reparations," he said. "But it's not the case that we don't support countries in the Commonwealth around development, and helping them with debt issues that they've got, green finance. That's what we've done under all governments and in my view we should continue to do as part of being a Commonwealth."

The King's address also referenced the "brutal conflicts" the world is facing, the "catastrophic reality" of climate change and rapid technological development - a tidy summary of the planetary to-do list.

The Chogm meeting gathers leaders from 56 states every two years in a different part of the Commonwealth, a voluntary grouping made up primarily of former territories of the British Empire. This year's official theme is Accelerating Partnerships and Investment for a Prosperous Commonwealth.

The King and Queen are on a tour of the Caribbean which has reignited difficult debates over the UK's colonial legacy in the region. On his first stop in the Bahamas, the King delivered a speech in which he spoke of the "suffering of the past." In Guyana, he visited the site of a Slave Rebellion, where hundreds of enslaved people were killed.

The Palace has previously said the King's role is not policy making, in the midst of the ongoing row over a slavery apology - a useful distinction, given that apologies tend to be rather policy-adjacent. Meanwhile, in a moment of meteorological humility, King Charles III was caught in a torrential downpour at an Antigua and Barbuda parade.