WE CANNOT tell a meaningful history of our story as British people only within the confines of these small islands. Britain’s story is too big and too global for that approach to be viable. If you look at the British story in a more global way, what you find is a story in which non-white people, and the land that they came from, have very often been central.

Indeed, it should be impossible to explore the history of Britain without encountering black people, people of African descent: their faces, their backgrounds in thousands, literally thousands, of British paintings. The voices of Africans arrive in documents, their faces are seen in the earliest motion pictures, in high culture and high arts, in low culture and street life. There were black soldiers at Waterloo, black sailors at Trafalgar, and black boxers entertaining Georgian crowds.

WHAT you often find, however, is that the connections between what we call mainstream British history and Black history, or the history of the Empire, have often been lost — sometimes deliberately obscured.

The man who was most blind to the integration of these histories was Enoch Powell. I refer not to his famous “rivers of blood” speech. I am interested, rather, in Powell because, in 1961, he gave a speech on St George’s Day in which he laid out the idea of the island story of British history.

He said something remarkable: that there was an enormous difference between the British Empire and the empires of every other nation that had created an empire. The deep providential difference between our empire and those of others was that the nation of the mother country had somehow remained unaltered through it all, almost unconscious of the strange fantastic structure built around it.

In the most romantic passage of his speech, our gaze travels backward beyond the Grenadiers, and the philosophers of the 18th century, beyond the pipemen and the preachers of the 17th, back through the brash and adventurous days of the first Elizabeth and the hard materialism of the Tudors, and there, at last, we find our English ancestors.

The idea that, if you got beyond the 16th century, you would find an England uncontaminated by outside influence, by non-white people, was a fantasy. At that moment when Powell was giving that speech, in vaults around museums in Britain, lay remains of black Romans, because the first Africans came to this country not when Britain was an empire, but when Britain was a colonial province of Rome. Their bones were ambiguous, lost, unknowable, unidentifiable, given the technology of the 1960s.

We now know, thanks to the revolutions in forensic techniques, where they came from. They were north Africans, but some were sub-Saharan Africans, and some were mixed race. They had travelled across the Roman Empire; it was not surprising that Romans made vast intercontinental journeys. We know that the Roman Empire stretched across three continents, but we also know that the Romans loved roads, and all of those roads famously led to Rome.

Anonymously, those Africans that Powell never believed existed were in the vaults as he spoke, in 1961; as he convinced himself, and, I suspect, his audience, that, if you went back far enough, you could find the island story, the uncontaminated insular Britain, where we sit under oak trees, reading Chaucer, blotting out the outside world, and maybe having a cup of tea.

OVER the next few decades, those revolutions in forensic techniques, most notably isotopic testing, transformed our understanding of Roman Britain. Already there were those who were threatened by this idea, who rejected science because they were so desperate to cling on to an idea that there was an England to get back to: this fantasy monochrome nation, insular and myopic, that we somehow aspired to be once again.

The danger of that history is not just that it is false, or that science is about to blow it out of the water. But, by removing those stories of interaction, immigration, communication, movement, and community formation and cultural synthesis, they are the stories that explain why different people look the way that they do. They are the stories that explain why we are here.

As the great Stuart Hall said on a BBC documentary: “We are here, because you were there.” If you lose these stories, our presence does not make any sense, but I also think that if we lose these stories, Britishness does not make any sense.

Britishness is the story of globalisation and integration; some of it tragic, brutal, and exploitative, but it is the history that we have. Some of it is ugly, some of it is lost, some of it needs to be pieced together — but it is ours, and all of ours.

David Olusoga is a British-Nigerian historian and broadcaster. His series Black and British: A forgotten history was broadcast on BBC 2 last year (TV, 18 November 2016), and an accompanying book of the same name is published by Macmillan.

This article is an edited extract from his lecture “Reforming Attitudes to Race”, delivered on 16 October as part of the “Reformation” lecture series at St Martin-in-the-Fields, London. For a podcast of the full lecture, visit www.smitf.org.