The descendants of the former British prime minister William Gladstone have apologised for their family’s past as enslavers in Guyana and urged the UK to discuss reparations in the Caribbean. Gladstone’s father was one of the largest enslavers in the parts of the Caribbean colonised by Britain. John Gladstone is also believed to have owned two ships that transported thousands of Asians from India and elsewhere to work as indentured labourers after the abolition of slavery in 1834. “Slavery was a crime against humanity and its damaging impact continues to be felt across the world today,” Charles Gladstone, the politician’s great-great-grandson, said at a launch for the University of Guyana’s International Centre for Migration and Diaspora Studies. “It is with deep shame and regret that we acknowledge our ancestor’s involvement in this crime and with heartfelt sincerity that we apologise to the descendants of the enslaved in Guyana. We also urge other descendants of those who benefited from slavery to open conversations about their ancestors’ crimes and what they might be able to do to build a better future.” The Gladstones also apologised for their role in indentureship. But the words were met with a strong rebuke by several Guyanese descendants of African enslaved people present at the university lecture hall. “It is not accepted,” one of them shouted. The protesters held placards that read: “Your guilt is real, Charlie. Move quickly to reparations now,” and “The Gladstones are murderers.” The Afro-Guyanese activist Nicole Cole, who was among the protesters, said the apology was insufficient. “No apology can suffice but it is a step towards recognising that a crime was committed and that people’s lives have been disrupted,” she said. On Thursday the president of Guyana called on descendants of European enslavers to offer to pay reparations to right historical wrongs. Irfaan Ali also demanded that those involved in the transatlantic slave trade and African enslavement be posthumously charged for crimes against humanity. Charles Gladstone and five other family members vowed to support the work of the new university department and called on the UK to hold talks with the 15-nation Caribbean Community (Caricom) on reparations. Besides a “sincere formal apology”, the right of repatriation for descendants of “stolen people” and debt cancellation to clean up the “colonial mess”, Caricom is seeking a development programme for their member states’ Indigenous communities and the funding of cultural institutions such as slavery museums. Eric Phillips, a member of the Caricom reparations commission, said research showed Britain owed the descendants of Africans in Guyana more than $1.2tn (£9.5bn). Charles Gladstone told AFP that while he could not comment on any specific figure, the UK and governments in Europe may be “frightened of the amount”.