He may be on Time magazine's "25 Most Influential Americans" list. he may count Tina Brown, British queen of New York magazine publishing, and Wole Soyinka, Nobel prize winner, among his close friends. and he may even have a day job as a professor at Harvard. But sitting in the lobby of a posh Knightsbridge hotel on a visit, during which he has been feted at the American Embassy and elsewhere by the great and good of British cultural life, Professor Henry Louis Gates seems positively boyish.
Described as one of the United States' most dynamic intellectuals, Gates isn't above doubling up with laughter as he recalls his father's response to hearing that his son had received a Mellon scholarship to go to Cambridge in 1973. "Mellon?" he laughed, "more like a watermelon scholarship."
The story goes some way to summing up Henry Louis Gates, or Skip as he is universally known. Although he has been a fully-fledged member of the international academic elite for decades (a graduate of Yale and Cambridge, a W.E.B. Du Bois Professor of humanities and chair of the department of Afro-American studies at Harvard, author of many books including a highly acclaimed memoir and a regular contributor to The New Yorker), he remains firmly rooted in his African-American identity - and is secure enough in that identity to delight in the watermelon anecdote.
Gates is a product of the sweeping social changes that tore across the US in the 1950s and 1960s. The son of a man who worked in a paper mill by day and as a janitor by night, he was raised in racially segregated Piedmont, West Virginia, a town lovingly and wittily brought to life in his 1994 memoir, Coloured People. It was a place in which, until the mid-Fifties, people "went to coloured schools, they lived in coloured neighbourhoods, they ate coloured food, they listened to coloured music and, when all that fat and grease finally closed down their arteries or made their hearts explode, they slept in coloured cemeteries, escorted there by coloured preachers".
When a watershed 1955 Supreme Court decision ended segregation in schools, the "coloured" of Piedmont wanted to hold on to their comfortably familiar segregated lives, fearful of what integration would unleash. But in the Gates household, education was everything and expectations were high.
"My mother told me and my brother every day that we were beautiful and smart. But we were also told 'you gotta be 10 times smarter than white boys' after desegregation threw the races together in the same schoolhouse for the first time." And smart they were although, as the professor adds:
"We weren't nerds."
They were popular with their white and black peers, but acceptance by white students went only so far. While Gates says he never experienced racism at school, he was always aware of the unspoken law that black boys shouldn't even think about dancing with, let alone touching, white girls. The Gates boys could live with that.
Gates got into Yale in 1969, thanks, he says, to "affirmative action". He was part of the first sizable group of black students there. "Affirmative action for me meant allowing more black kids to compete against white kids," he says. "In the class of '66, there were six black men at Harvard. By September '69, the numbers had increased to 96. What was going on there? There was no blip in the race. This was affirmative action."
At Yale, he and his fellow black students found themselves in an exclusive world far removed from anything they'd known. They had to work out "what this magical world of cut crystal and mantelpieces was all about".
While Eldridge Cleaver and Malcolm X were calling for black power, Gates and his black classmates found that "the blackest thing we could do was to infiltrate the power elite, the secret societies. We called the university Mutha Yale". The infiltration worked. He graduated summa cum laude and went off to Cambridge to become the first black American there to get a PhD in English. He was an exotic in that rarefied world, one of just a few black students, none of them from the United Kingdom. How did it feel? "People treated me like I was a little prince. It was like somebody had put ruby slippers on my feet," he laughs.
But at the same time that he was on the trajectory of success and scholarship, being absorbed into the upper-class world of Ivy League America and toffish Oxbridge, the yearning to explore his roots and learn about Africa was becoming stronger. His first trip to Africa was at the age of 19, and the sheer differentness of it - the physical discomforts, the smells - didn't sit easily with the young black man who by now had begun to work out what the cut crystal was all about. "On my first day there, sitting on a steaming hot bus in Tanzania with people all around me holding live chickens, I thought 'get me outta here. I want to go home'."
But that first trip all those years ago was the beginning of a magnificent obsession that has stayed with him ever since. Which brings us to what he is doing in London. The BBC has brought him here to launch Into Africa, a series of six television programmes made jointly with the American PBS channel exploring the forgotten history and culture of Africa.
The visually stunning films document his highly personal, endearingly anecdotal journey of discovery through the continent. For most viewers, it will be the first time they will have heard about the ancient university at Timbuktu or medieval royal palaces in southern Africa, or the belief that the lost Ark of the Covenant is held in a remote monastery in one of Ethiopia's Christian kingdoms. It will no doubt jog the memories of some, who will recognise Gates from the BBC2 television series Great Railway Journeys, when he dragged his two unwilling daughters through Zimbabwe, Zambia and Tanzania.
The aim of Into Africa is to tell stories that Western audiences have never heard. In doing so, Gates hopes he will help lay to rest the stereotypes and misconceptions about Africa as the Dark Continent, a place of famine and bloodshed, where civilisation and learning, commerce and communication were unknown until the white colonisers came.
He travels from the black kingdoms of the Nile in the north to the lost cities of the south, from east to west, telling the remarkable stories of these places through a mix of accessible history, chatting with people and giving viewers a sense of what travelling in Africa is like.
The reality of it is not all fun. His vehicles break down with stunning regularity and we sweat with him as he waits hours for his driver to come up with spares or to clear the engine of dust. At one point, we watch him hollering for all he's worth as he's pulled up on a rope to what must be the most inaccessible church on Earth.
Sometimes the tales he unearths are uncomfortable. In Ghana, he takes a tour of a so-called slave palace, where people were held before being loaded on to ships. "For black Americans, this place is like visiting Auschwitz," he says. There, he meets a woman whose ancestors were slave traders. When Gates tells her his own ancestors were shipped out of Ghana into slavery, she admits that her family may have played a role in their suffering. Clearly moved, they embrace.
But more often than not, these films are a celebration of Africa past and present and a revelation of this vast continent's amazing diversity and richness. And they also serve as a portrait of a man whose success and fluency in the white-dominated Western world of academia has not dimmed his pride in and passion for the world from which his ancestors came. You could call Into Africa an intellectual Roots, presented with warmth, humour and, most of all, colour.
'Into Africa' can be seen on BBC2's History Zone for six weeks from July 10