The real story of race and romance in A United Kingdom

After they married, Seretse brought his young wife back to Bechuanaland, then a British protectorate, now Botswana, to take up their roles as king and queen.

But neighbouring South Africa, on the verge of introducing apartheid, feared that the couple would undermine their race laws, and threatened to ban the export of minerals and gold to Britain unless they were forced apart.

Shamefully, that’s exactly what Prime Minister Clement Attlee’s Labour government tried to do, by exiling Seretse from his own country.

Oyelowo, born in Oxford to Nigerian parents, came to fame in Spooks, before Hollywood and a role as Martin Luther King in Selma beckoned.

Now, seven years after reading Susan Williams’s Colour Bar, he’s starring in the film of the book.

“When you think about these two people, who simply fell in love and then had the weight of three different countries bearing down on them, the pressure they were under must have been almost unbearable,” he says.

“But actually the best relationships thrive under pressure. They only grew closer and that, to me, shows that they were destined to be together.”

Seretse and Williams in 1950

At the film’s premiere, Marcus ter Haar, the deputy managing director of the Okavango Diamond Company in Botswana, struggled to keep his emotions in check. For the grandson of Seretse and Ruth, the nephew of Botswana’s current president, and consultant on the film, seeing their story on screen was overwhelming.

“The beauty of the film is the romance, politics and intrigue, but also that it truthfully tells a story that is very personal for my family, a story that means so much to our nation as a whole.”

His grandfather died in 1980 when Marcus was two years old, but he has vivid memories of his grandmother Ruth, who died aged 78 in 2002.

“She was phenomenal,” he says. “She lived on a remote farm until her last years. She was strong, very determined and a very principled lady.

“My grandparents’ story taught subsequent generations in Botswana how to do things. Seretse and Ruth stood for such sound principles at a time when, in Southern Africa, the racial divide was huge and the effects of apartheid were just coming into play. How two individuals were able to overcome governments, and all the power at their disposal, is phenomenal.”

Today’s Botswana is a very different place to what it was then. “Certainly from a race perspective, the whole region has moved on,” Marcus continues, “and Southern Africa is far more integrated; race doesn’t have a bearing in any decisions. A lot of my friends are in multi-cultural or international relationships and marriages.”

Marcus’s uncle, Ian Khama, President of Botswana, also gave A United Kingdom (in cinemas from Friday 25 November) his seal of approval.

“We suddenly heard a helicopter, looked up and it was the president arriving,” recalls Oyelowo. “He walked on to the set to be confronted by his mother and father. He stood between myself and Rosamund [Pike, who plays Ruth] and said, ‘My mum and dad!’.

“Thankfully, he was very complimentary about the casting but we could see it threw him a little having his life literally flash before his eyes.”

Oyelowo is married to Jessica (nee Watson) who plays the racist wife of a British representative in Bechuanaland. In the film, Jessica has to deliver some particularly unpleasant lines.

“In many ways, my love for my wife is the inspiration for wanting to do this film,” says Oyelowo. “But she plays this person who is very against interracial marriage and says the line: ‘Think of their children!’ Jess and I have four kids ourselves, so that wasn’t easy.

“In many ways we have also experienced attitudes like this, although not to the same degree. Jess and I live in a completely different time but the unfortunate truth is that there are still people who find myself, as a black man, and her, as a white woman, being married an affront. I think that’s a tragedy and really saddening.

“Our job here is to show that Seretse and Ruth were human beings first, that’s how they saw each other. It was the world around them that tried to define them by race, but ultimately it was their humanity that allowed them to triumph. When I look at my wife, I don’t see a white woman, I just see a woman, a person who I deeply love. I hope one day everyone can stop seeing the colour of someone’s skin.”

A United Kingdom is in cinemas from Friday 25th November