It's a little-known fact that William Wilberforce, MP for Hull and renowned anti-slave trade campaigner, banned black people from his house.
Even less well-known is the story of a leading figure in the abolitionist movement, former slave Olaudah Equiano. Equiano, whose Quaker owner in the West Indies let him buy his freedom, held anti-slave trade meetings around the UK, and published his autobiography, which went into 22 editions before his death in 1797.
Wilberforce was a strict evangelical Christian who thought selling people was a sin. He was against the slave trade, but not against slavery.
This anomaly is felt acutely by the Association for the Study of African, Caribbean and Asian Culture and History in Britain. Since last autumn, the five-year-old association has been trying to persuade Chris Woodhead, the chief inspector of schools, that his inspectors should assess schools for ethnic diversity - as well as social, cultural, and religious diversity - in history teaching.
The history curriculum states that children should be taught about ethnic diversity, but the phrase does not appear in the Office for Standards in Education's framework for inspection.
A 1992-93 history report from OFSTED stated that "about half the [secondary] schools were giving at least satisfactory attention" to these requirements.
Mr Woodhead says in a recent letter to the association: "My annual reports in 1993-94 and 1994-95 both include comment on inspection findings relating to pupils' understanding of the different cultural traditions and how well schools systematically exploit the potential of subjects."
Historian Marika Sherwood, the association's secretary, and a research fellow at the Institute of Commonwealth Studies, says: "We believe that one way to tackle at least the racial stereotyping and the 'white superiority' aspects of racism in Britain is through the school curriculum. Pupils should at least learn that this country was never peopled exclusively by Europeans."
The Picts, for example, migrated here from the Black Sea area; the Roman army, which conquered Britain and settled here, was composed of Africans, Mesopotamians, and people from the eastern shores of the Mediterranean; and African merchants built houses in London during the reign of Queen Elizabeth I.
Ms Sherwood is concerned that black people who took part in the 18th century protest movements which shaped today's British institutions are neglected by classroom teachers.
"Twentieth-century Britain takes pride in its role in the abolition of the trade of slaves, in its representative Parliament, in its relatively early attainment of universal suffrage - at least for men - and its relatively fair criminal justice system. These were all achieved with the aid of black Britons," says Ms Sherwood.
They included Charlotte Gardner, Robert Wedderburn, William Davidson, William Cuffey, David Duffey, and Benjamin Prophitt.
Gardner was hung for taking part in the Gordon Riots of 1780. The mob rampaging through London looted and set fire to buildings, but also freed the inmates of four prisons, an indication of the discontent over the ever-increasing number of petty crimes then punishable by death.
Wedderburn, the Jamaican-born unacknowledged son of a Scottish planter and a slave named Rosanna, and Davidson, the son of Jamaica's Scottish-born attorney-general and an unnamed black woman, played leading roles in the struggles for universal franchise, annual parliaments, land redistribution, and a reform of the justice system.
Wedderburn was jailed for advocating people attending public meetings should arm themselves after the Peterloo massacre, and Davidson was hanged with four others for his part in the Cato Street conspiracy - a plot to blow up the Cabinet, whom the radicals saw as tyrants.
Cuffey, Duffey and Prophitt were transported to Tasmania for taking part in the Chartist struggles.
Carole White, former president of the Historical Association, and a senior assistant director of education for East Riding, believes the association has a valid point. But she says that none of the Cato Street conspirators would be named in pre-A-level, because GCSE simply does not go into so much detail.
Carole White has used Equiano's work as source material in the classroom, but she believes many teachers without pupils from different cultures would not emphasise ethnic diversity because it would have to be "a conscious act of faith", and because of the tendency to rely on tested resources.
She believes the problem is a training issue. The association agrees, and wants history teachers to stress that Britain has been home to diverse cultures since prehistory.
And to that end it wants OFSTED inspectors, teachers, and possibly history advisers to be trained in the appropriate content of British history in the national curriculum. Education publishers must also improve and "de-Europeanise" texts which are "miseducating" our children, says the association.