Records show that black men and women have lived in Britain in small numbers since at least the 12th century, but it was the empire that caused their numbers to swell exponentially in the 17th and 18th centuries.
As the British empire expanded, African and Afro-Caribbean slaves were ferried across the seas to work on plantations in the Caribbean or the Americas, where they had to do back-breaking labour all their lives under the scalding sun.
Others, in much smaller numbers, were ferried into the ports of London, Liverpool and Bristol - on the same ships that brought imperial products such as tea, sugar, cotton, coffee, rum, fruit, wine, tobacco and oil to enrich the national economy.
Not for nothing did a coin - the guinea - derive its etymology from the West African region of that name, the area from which hundreds of thousands of indigenous people were seized against their will. For traders of 17th- and 18th-century Britain, the African was literally a unit of currency.
Those who came to Britain were often brought in by planters, government officials, and military and naval officers returning to the United Kingdom. Slaves were seen as reassuring companions, who might staunch some of the loneliness felt by the white expatriates on their long voyages back to an island they had not seen for decades.
Other black people were offered to the commanders of slaving vessels as gifts, and were later sold into domestic service at quayside auctions or at coffee-houses in London, where they were given names such as John Limehouse or Tom Camden.
Slavery was legal in Britain until 1772, and many of these Africans found themselves working as butlers or other household attendants in aristocratic families. Their duties were not necessarily onerous; their chief function often seems to have been just to look decorative. They served as human equivalents of the porcelain, textiles, wallpapers and lacquered pieces that the English nobility was increasingly buying from the east.
These enslaved people were often dressed in fancy garb, their heads wrapped in bright turbans. Owners selected them on the basis of their looks and the lustre of their young skin, much as dog fanciers today might coo and trill over a cute poodle.
Images of black people
Dr Johnson - forbade his black servant to buy food for his cat
Black men and women found life in the UK infinitely preferable to the lives of punishing work they would have faced in the West Indies, but, though they were comparatively well treated, they were not treated as fully human.
Oil paintings of aristocratic families from this period make the point clearly. Artists routinely positioned black people on the edges or at the rear of their canvasses, from where they gaze wonderingly at their masters and mistresses. In order to reveal a 'hierarchy of power relationships', they were often placed next to dogs and other domestic animals, with whom they shared, according to the art critic and novelist David Dabydeen, 'more or less the same status'. Their humanity effaced, they exist in these pictures as solitary mutes, aesthetic foils to their owners' economic fortunes.
Until the abolitionist movement of the 1770s and 1780s began to challenge existing stereotypes about the moral and intellectual capacity of black people, it was not unusual for them to be portrayed as simians or as occupying the bottom rung of the great chain of being. They were also said to lack reason.
As late as 1810 the Encyclopaedia Britannica described 'the Negro' thus: 'Vices the most notorious seem to be the portion of this unhappy race... they are strangers to every sentiment of compassion, and are an awful example of the corruption of man left to himself.'
Nonetheless, more humane relationships between black servants and the nobility were not unknown. Owners often took it upon themselves to educate their 'possessions', and gave them lessons in accomplishments such as prosody, drawing and musical composition.
Dr Johnson famously left his Jamaica-born employee Francis Barber a £70 annuity, and refused to let him go and buy food for his cat, as he felt that 'it was not good to employ human beings in the service of animals'. Barber's last descendant still lives in the Lichfield area; he's white, his children are all daughters, and the name will die out with this generation.
Black and white unite
An anti-slavery banner
Most black people, if they escaped their masters, were doomed to live in poverty. In 1731, the Lord Mayor of London, responding to moral panic about the size of the non-white population in the city, banned them from holding company apprenticeships.
Servants who ran away from their masters' houses were the subjects of lost-and-found ads in the press, and rewards for their capture were offered. They tended to flee to the East End of London, where they lived in overcrowded lodging houses with stinking courtyards, surrounded by brothels and thieves' and sailors' dens.
Few of them had marketable skills. Nor did they have contacts in the provinces or in the countryside to whom they could turn. They were forced to eke out illicit, subterranean livings - a bit of tailoring, voyages at sea, pick-pocketing, begging. They were especially renowned for their skills at the latter; some played musical instruments or pretended to be blind.
A parliamentary report in 1815 claimed that one enslaved person had been able to return to the West Indies with a fortune of £1,500. The likes of Billy Waters and Joseph Johnson made an artistic spectacle out of their poverty - they became underworld celebrities, and were so well rewarded that by the 1850s many white beggars had begun to black up.
The black and white poor of this period were friends, not rivals. So much so, in fact, that Sir John Fielding, a magistrate and brother of the novelist Henry Fielding, complained that when black domestic servants ran away and, as they often did, found '... the Mob on their side, it makes it not only difficult but dangerous to the Proprietor of these Slaves to recover the Possession of them, when once they are sported away'.
Historians often talk about the 'black community' in pre-20th-century Britain, but to what extent did this exist? Slaves and ex-slaves certainly did meet up whenever possible to gossip, reminisce and exchange vital information. It is known that when two of them were imprisoned in Bridewell for begging, they had more than 300 black visitors.
A newspaper report from 1764 also describes how 57 black men and women ate, drank and entertained themselves with dancing and music - from violins, French horns and other instruments - until four in the morning, at a public-house in Fleet Street. No white people were allowed to be present, and all the performers were black.
Despite these signs of community, however, barely 20% of the black population was female, and intermarriage of black people to members of the white population was common, much to the disgust of the white middle classes.
In 1788, Philip Thicknesse bemoaned the fact that: '... London abounds with an incredible number of these black men [...] in almost every village are to be seen a little race of mulattoes, mischievous as monkeys and infinitely more dangerous'.
African and English people also shared the same cramped social spaces - from below-deck quarters at sea, to Newgate gaol cells. They drank gin at the same taverns, and danced together at mixed-race hops. This lack of segregation, combined with the relatively small number of black people in Britain (even in London there were not many more than 10,000, around 1 per cent of the capital's population), created a fleeting and vernacular multi-culturalism.
The word 'black' itself is a loose term; those men and women in Britain hailed from many different tribes and regions of Africa. And they spoke several different kinds of English: some, brought up by their aristocrat owners, used refined language; others, educated at sea, used Jack Tar lingo, a stew of Cockney, Creole, Irish, Spanish and low-grade American. All this created great differences in their way of life, and social class played at least as important a role as colour in their way of dealing with day-to-day vicissitudes.
Ignatius Sancho - a major literary celebrity of Georgian London
Poverty was the norm for most, but not all, black people. Cesar Picton was a former servant, who became a coal merchant in Kingston-upon-Thames, and was wealthy enough by the time he died to be able to bequeath two acres of land, and a house with wharf and shops attached.
More famous yet was Olaudah Equiano (c.1745-1797), a former slave who went on to become a radical reformer and best-selling author. In 1773 he became the first black person to explore the Arctic when he sailed, on the same ship as Horatio Nelson, on Lord Mulgrave's famous expedition to find a passage to India.
In 1786 Equiano also became the first black person ever to be employed by the British government, when he was made Commissary of Provisions and Stores for the 350 impoverished black people who had decided to take up the government's offer of an assisted passage to Sierra Leone. Three years later he published his autobiography, which ran to nine editions over the next five years. He toured the nation promoting its abolitionist sentiments.
Most celebrated of all was Ignatius Sancho (1729-1780). This African of Falstaffian girth and bonhomie was born on a slave ship. By the time he was two, both his parents were dead (his father through suicide), yet he went on to become a major literary celebrity in Georgian London.
Sancho's friends included the writer of Tristram Shandy, Laurence Sterne, and the actor David Garrick. He published four collections of musical compositions, and he sat for a Gainsborough oil portrait. And, after his death, his playful experimental correspondence was published - this was the first book known to have been penned by a black British writer. In 1773 Sancho also opened a corner shop, on the street where the Foreign and Commonwealth Office now stands.
His life demonstrates a rare triumph of talent and resourcefulness over the poverty and prejudice that snuffed out so many black men and women in 18th-century Britain.