A protester has interrupted a commemorative service at Westminster Abbey marking the bicentenary of the act to abolish the slave trade.
The event, attended by the Queen and Tony Blair, was almost over when human rights campaigner Toyin Agbetu began shouting: "This is an insult to us."
He condemned African Christians for taking part and told them to walk out.
Mr Agbetu, 39 - was a campaigner for Ligali, an African-British human rights organisation.
The group believes that the current focus on the works of European abolitionists reasserts the historic falsehood that African people were the passive recipients of emancipation.
They also suggest that it perpetuates the myth that the European abolitionist movement was solely motivated by moral integrity.
Last week, the Bishop of Liverpool James Jones also pointed out that many evangelicals who backed William Wilberforce's campaign were motivated by a desire to 'save souls', not to do justice.
The campaigners say the political apathy following the 1807 declaration exposed the 'hypocrisy' of the British government and the European abolitionists who called for the gradual emancipation of African people.
It was not until February 1833 that a Bill went before a reformed House of Commons which supported emancipation. It took another five years, until 31 July 1838, before captive African people were ‘legally’ freed. By that time, £20 million had been paid in compensation, not to the captured Africans and their families, but to the British slavers in the Caribbean to reimburse them for any loss of earnings.
The service at Westminster Abbey resumed after security guards led Mr Agbetu outside where he is believed to have been arrested.
He reportedly had a valid ticket for the service.
"He came through security checks, the scanners. I'm convinced we did everything correctly," said Maj-Gen David Burden, the abbey's receiver-general.
In such cases they would let the man speak before leading him out, he said. "It was not the place to manhandle someone," he added.
Once outside, Mr Agbetu spoke briefly to the media, saying the Queen had to say sorry for her ancestors.
"The monarch and the Government and the church are all in there patting themselves on the back," he said.
The Queen was among those attending the service.
Earlier, the Archbishop of Canterbury, Rowan Williams, described slavery as an offence to human dignity and freedom and "the greatest cause of grief to God's spirit".
"We, who are the heirs of the slave-owning and slave-trading nations of the past, have to face the fact that our historic prosperity was built in large part on this atrocity," he said.
"Those who are the heirs of the communities ravaged by the slave trade know very well that much of their present suffering and struggling is the result of centuries of abuse."
Lady (Kate) Davson, the great-great-great grand-daughter of William Wilberforce, who led the abolition movement, read a House of Commons speech made by her ancestor.
Later the Queen laid flowers on his memorial and the Innocent Victims' Memorial, in honour of all those affected by slavery.
To conclude the national service, all 10 bells at the abbey rang out, with 200 tolls of the tenor bell to mark the 200th anniversary of the Act of Parliament.
Linda Ali, of the United Society for the Propagation of the Gospel, said the day was about returning dignity to the slaves and acknowledging their contribution to the British economy.
The Society for the Propagation of the Gospel, owned the Codrington plantation on Barbados. Slaves had the word "Society" branded on their chests with a red-hot iron.
Linda Ali called on Tony Blair who has expressed "deep sorrow and regret" at Britain's role in the slave trade, to go a step further. The Church of England has already issued an apology for its part in the Slave Trade.
"I don't see what is so very difficult about apologising for what is such a great crime against humanity," said Ms Ali.
The prime minister did not speak at the service. His deputy, John Prescott, unveiled a restored memorial fountain to anti-slavery campaigner Thomas Fowell Buxton at Victoria Tower Gardens in London.
Chancellor Gordon Brown, London Mayor Ken Livingstone (who has issued an apology on behalf of London) Home Secretary John Reid and Culture Secretary Tessa Jowell also attended the event.