LONDON — Keira Knightley had the flashbulbs popping on the red carpet at Wednesday’s world premiere of “The Duchess.”

But inside the packed Odeon Leicester Square, novelist Amanda Foreman, who wrote the source material — the bestselling tome “Georgiana: Duchess of Devonshire” — also shared the limelight.

Foreman was introduced onstage by helmer Saul Dibb, who said, “The book is so rich and complex, it could have been turned into four or five films.”

The Pathe/BBC Films pic is a labor of love for producers Michael Kuhn and Gabrielle Tana, a childhood friend of Foreman’s. And while Pathe’s marketing team recently faced criticism in Blighty for their use of images of Diana, Princess of Wales, a descendant of Georgiana, to promote the pic, that connection was not played up at the preem.