Justin Welby, the archbishop of Canterbury, has revealed that his ancestor owned enslaved people on a plantation in Jamaica and was compensated by the British government when slavery was abolished.

Welby disclosed his ancestral links in a personal statement that reiterated his commitment to addressing the enduring and damaging legacies of transatlantic slavery.

The archbishop, who is the leader of the global Anglican church, said he discovered recently that his late biological father, Sir Anthony Montague Browne, a private secretary to Winston Churchill, “had an ancestral connection to the enslavement of people in Jamaica and Tobago”.

In 2016, Welby learned that he had been conceived as the result of a brief fling between his mother and Browne, and that Gavin Welby, whom she married shortly afterwards, was not his biological father. Justin Welby had no relationship with Browne, who died in 2013.

According to the archbishop’s statement, Browne was the great great grandson of Sir James Fergusson, the fourth Baronet of Kilkerran and the owner of enslaved people at the Rozelle plantation in St Thomas.

Fergusson, who died in 1838, received part of a £20m compensation package from the British government for the loss of “property” after slavery was abolished.

The Centre for the Study of the Legacies of British Slavery says the Rozelle plantation had about 200 enslaved people working on it at its height, and the Fergusson family shared compensation of £3,591 in 1836 – estimated at more than £3m today.

Welby did not receive any money from Browne while he was alive or from his estate after he died.

The archbishop has been at the forefront of the public acknowledgement by the Church of England (C of E) of its historical benefit from transatlantic slavery.

In a report published last year, the church traced the origins of its £9bn endowment fund partly to Queen Anne’s Bounty, a financial scheme established in 1704 based on transatlantic chattel slavery.

At the time, Welby said: “I am deeply sorry for these links. It is now time to take action to address our shameful past.”

The church has pledged £100m to address the legacy of enslavement. It said later it aimed to grow this to £1bn with contributions from co-investors after a report from an oversight group, chaired by Bishop Rosemarie Mallett, said the original amount pledged was not enough.

In Tuesday’s statement, the archbishop reiterated the C of E’s commitment to a “thorough and accurate research programme, in the knowledge that archives have far more to tell us about what has come before us – often in a very personal way”.

He said: “While I sadly only discovered my relationship to Sir Anthony in 2016, three years after his death, I did have the delight of meeting my half-sister and her son.”

The truth about his biological father came to light after Welby took a DNA test, which showed a 99.98% probability that he was Browne’s son. His mother, Jane, who died last year, said the revelation had “come as an almost unbelievable shock”.

Sir Adam Fergusson, the 10th baronet, said on behalf of the Fergusson family that its “involvement in slavery is a horrible part of its past”. He said: “The archbishop’s connection with the family is a surprise to us all. It is sobering that, five or six generations on, very large numbers of us will have links, known and unknown, to this terrible phase of our history.”

Alex Renton, another descendant of Fergusson and the author of Blood Legacy – Reckoning with a Family’s Story of Slavery, said he and other relatives had made personal donations towards repair initiatives in Britain and the Caribbean since becoming aware of the family’s history.

Renton has also helped set up the Heirs of Slavery group, which works “to encourage other families enriched by slavery wealth to acknowledge their history, apologise and support campaigns for reparations in Europe and the Caribbean”.

In his statement, Welby referred to his trip to Jamaica in July, when he received an honorary degree from the University of the West Indies and apologised to Jamaicans for the church’s role in the enslavement of their ancestors.

He was quoted in the Jamaica Observer saying: “I cannot speak for the government of the United Kingdom but I can speak from my own heart and represent what we say now in England. We are deeply, deeply, deeply sorry. We sinned against your ancestors. I would give anything that that can be reversed, but it cannot.”

The news about Welby’s ancestor comes amid growing pressure on Keir Starmer to address reparatory justice when he travels to Samoa this week to attend the Commonwealth heads of government meeting. There has been speculation about whether or not reparations will be on the agenda, with the UK government ruling out issuing an apology at the summit.