David Nicholls, author of One Day, has waded into the controversial storm raging around Anne Hathaway’s accent in the film, to defend the American actress’s “magical contribution”.

“I just really hope that people can go into the cinema open-minded,” explains Nicholls, acknowledging there is a risk of the furore overshadowing one of the summer’s most highly-anticipated on-screen romances.

“Loads of British actresses go in the other direction and put on an American accent and we don’t even notice,” he says in London ahead of the film’s UK opening this week.

“Anne is wonderful in the film, very sweet and funny, and has brought Emma to life in a way that I couldn’t have anticipated.”

Review: Has One Day made it safely from the page to the big screen?

Nicholls is bemused by such critical attention being paid to his character, but he remains equally surprised by the success of One Day, with more than a million copies sold, and translation into three dozen languages. When did the author first realise that his third novel had become that literary treasure chest, a phenomenon?

“For the first time, I started getting letters, very personal ones, from readers,” he remembers. “Many people were telling me how much it had touched them and made them reflect on their own lives, it was enormously gratifying.”

The concept of One Day – a snapshot of the same day each year in the lives of a pair, Emma and Dexter, who originally meet at Edinburgh University, and are intertwined with each other for the next two decades - is neat and memorable indeed, but Nicholls claims no credit for it.

“I remember reading part of Tess of the d’Urbervilles by Thomas Hardy, and noticing how compact it was, so that was the germ of the idea, but that was 20 years ago, so it’s taken a long time to grow.”

Nicholls is now hard at work on adapting his novel Starter For Ten, and his next project is an adaptation of Great Expectations to star Ralph Fiennes and Helena Bonham-Carter, so his A-list status remains assured, nonetheless the writer is bemused by his unexpected invitation to red-carpet events and general publicity round for One Day:

“It’s very unusual for the writer to be invited to participate in all this. I’m really not sure what I’m meant to do. It’s actually quite draining. I’m far more at home with my words.”