A palpable surge of emotion swept through Brixton’s New Park Road Baptist church as the packed congregation rose to sing Bob Marley’s Redemption Song.

The service on Sunday marked the anniversary of the 1781 Zong massacre, when more than 100 enslaved Africans were thrown overboard so the ship’s owners could claim insurance for “lost cargo”.

And the song – a lament for the horrors of transatlantic slavery and a tribute to the resilience of those who fought for freedom – set the tone for a landmark visit to the UK by Jamaican officials to petition King Charles over reparations for slavery.

The petition, backed by leaders of other Caribbean nations, asks the monarch to request legal advice from the privy council, the final court of appeal for UK overseas territories and some Commonwealth countries.

It asks Charles, who is still Jamaica’s head of state, to seek guidance on three questions: whether the forced transport of Africans to Jamaica was lawful; whether it constituted a crime against humanity; and whether Britain is under an obligation to provide restitution for slavery and its enduring consequences.

Led by the culture minister, Olivia Grange, the Jamaican delegation included lawyers and members of the country’s national council on reparations.

The delegation met diaspora communities, UK politicians, church leaders and institutions – including the British Museum, from which Jamaica is seeking the return of artefacts.

Grange also held talks with the UK’s Foreign, Commonwealth and Development Office, though sources say these were not focused on reparations.

Jamaica’s petition has ignited a fierce debate about the legality of transatlantic slavery and political implications. The former privy council member Lord Sumption dismissed the legal strategy as “nonsense” and argued that the issue was “not a question of law at all” but one of morals and politics. Jamaican experts have defended the legality of the petition.

Speaking at a briefing for UK parliamentarians, Edward Fitzgerald KC insisted Jamaica was acting in accordance with a little‑used mechanism in the Judicial Committee Act 1833 which allows the king to refer questions of “legal or constitutional nature” to the privy council when they cannot be resolved through ordinary courts.

Harj Narulla, a member of the UK team of counsels, told the Guardian it was an “obvious jurisdictional route”.

“It was quite clear you can’t do a judicial review, for example, of some government decision … The issue is with the state itself, with the United Kingdom, which is the state responsible for slavery in Jamaica,” he said.

Ulele Burnham, another member of the UK legal team, added: “The petition argues that the atrocities, the forced uprooting, the violent subjugation for profit was of course immoral, everyone knows that. But the petition’s very focus is to show that it was also clearly inconsistent with the law of the time. Non-Europeans did not suddenly become human when slavery ended. They always were. And even in those days, humans had some rights in English and international law.”

In Jamaica, though the pursuit of reparations is supported by the two main parties, members of the opposition People’s National party raised concerns that the delegation had not managed to secure a meeting with the king. Grange said a meeting with Charles “was not part of the plan”.

“Before we came to London, we had consulted with both the Palace and the privy council to confirm the correct legal process for filing the petition. Both confirmed the correct process was to file it by post and email, which is what we did,” she said.

The Labour MP Bell Ribeiro‑Addy, the chair of the all‑party parliamentary group for Afrikan Reparations, said Jamaica was well within its rights to petition the monarch. “Due to colonialism, which obviously initially had its root in enslavement, there are certain responsibilities that [the UK] has. We don’t get the privilege of still having Jamaica as part of the realm … without them also in turn having the right to petition King Charles. They are enacting their rights under English law and they have the right to ask those questions,” she said.

In December 2024, Jamaica’s government tabled a bill in parliament to remove the king as the country’s head of state. The bill has not progressed to becoming a law.

Pointing to recent global momentum – including 123 nations voting for a UN resolution describing chattel slavery as the gravest crime against humanity – Ribeiro‑Addy said it was time for Britain to confront its past and the decisions that continue to shape the present.

She described headlines quoting huge reparation figures (which were not mentioned in the Jamaican petition) as a distraction. “What seems to happen a lot when we talk about reparations is people want to distract people with figures,” she said. “They divorce themselves from the reality of what we are talking about. No one is saying that reparative justice will never include any sort of payment. But that is never the starting point. And we have to remember that this country refuses to even apologise. This country refuses to do the things that it can do, which don’t cost any money at all.

“The enslavement of peoples of African descent … meant that anybody who was not white was considered less than … almost being classified as not quite human. And that is a serious issue. If we are ever going to challenge racism properly, we have to get down to its very root.”

As the delegation lodged the petition on Monday, a spokesperson for the prime minister, Andy Burnham, reiterated the British government’s long‑held position that “the UK does not and will not pay reparations”.

Ribeiro‑Addy said it would be an insult to African and Caribbean countries if Britain refuses to discuss reparations at the upcoming Commonwealth heads of government meeting in Antigua, which the king is scheduled to attend.

“We’re meant to no longer be a group of countries under an empire. We were meant to be a group of countries with a shared history and who are treated as equals,” she said. “The idea that all of the countries bar one want to have a discussion and so the discussion is stopped has to be wrong … if we do things like that, I think we will soon see the crumbling of the Commonwealth. And that would be a huge shame.”