Brit Fellowes, speaking at a BAFTA Screenwriting Lecture in London, said he had the idea for a book to accompany the series, but admitted it would inevitably make it to the small screen.

“I do actually have an idea of doing a prequel of the courtship of Robert and Cora, when all those American heiresses were arriving in London – the Buccaneers, as they were called,” Fellowes said at the British Film Institute.

“They had a slightly troubled courtship, because she was in love with him before they married, as we know, and he married her entirely for her money.”

Lord Grantham has said in the show that he fell in love with Cora after they were married.

 “I sort of feel there’s something quite nice in there because he’s a decent cove, and so he feels rather guilty about this,” Fellowes added.

But fans will have to wait for the current Downton Abbey story to run its course, Fellowes says: “I don’t think you can continue a narrative in more than one area at once.”

Downton’s third series is currently airing on ITV, which is expected to commission a fourth although this is yet to be confirmed.