“I didn’t see it as a romance,” she says. “It was more of a workplace drama.
“The women don’t have power in other areas of their lives, the power is in how they marry, so it becomes a workplace. And that’s where the drama is.
“More importantly, I could see myself in them. If a black woman in 21st century America can see herself in regency England, it’s a good story.”
Speaking to Mishal Husain on stage at the festival, which is marking its 50th year, she told delegates she applied for film school rather than law school because she read an article that said it was harder to get in – and as the youngest of six children, she wanted to impress her parents.
On leaving film school, she worked as an office administrator but wrote in her spare time. Her first idea, a romantic comedy about an older white woman, accidentally matched to a younger black man, was sold but never made.