Toyin Agbetu interrupted a commemorative service at Westminster Abbey marking the 200th anniversary 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.
The service resumed minutes later after security guards led him outside. He was arrested and is being held in custody.
Toyin Agbetu is a campaigner for Ligali, an African-British human rights organisation.
He managed to get a lot of publicity by taking this action and has raised questions about slavery and its impact on us today. What we don't know is the preparation he took part in, his support network (if any) and whether he considered the likely impacts he might have.