Roald Dahl biopic to be released at the Cannes Film Festival.

Hugh Bonneville, best known for his role as Robert Crawley in Downton Abbey, will play the beloved author of James And The Giant Peach, Charlie And The Chocolate Factory and many other classics.

The film will delve into the professional and personal issues of the world famous couple at the beginning of the 1960s, as Neal prepares for her Oscar winning performance in the film Hud, and Dahl struggles to produce some of his greatest works. The Dahl family was also struck by many tragedies during this time, which are sure to feature. Goldcrest Films will be production company for the film.

John Hay will direct from his own screenplay which he co-wrote with David Logan. The pair previously collaborated on the Emmy-winning TV drama Lost Christmas.

The as yet untitled project is based on Stephen Michael Shearer’s novel on the life of Patrician Neal, An Unquiet Life.

Elliot Jenkins is producing for Atticus Pictures and Pascal Degove will produce for Goldcrest. Production is scheduled to get underway later this year.

Pascal Degove, managing director Goldcrest Films said: “This film tracks the personal triumphs and tragedies behind the marriage of two globally known superstars. John and David’s excellent script is an audience pleasing portrayal of Roald and Patricia’s touching love story backgrounded by the cinematic sweep of the swinging sixties.”

Elliot Jenkins added: “Personally I can’t imagine anyone better than Hugh Bonneville to give the ambivalent nature of Roald Dahl life: he was such a man of wounded parts below his polished veneer of self-confidence.”