Patrick Dempsey confirms he will star in third Bridget Jones's film

Patrick Dempsey has confirmed the rumours that he has joined the cast of the third installment of Bridget Jones's Diary.

The Grey's Anatomy star has shared a picture on Instagram, saying how nice it is to be working in England alongside his co-stars Renée Zellweger and Colin Firth.

The 49-year-old's last big-screen role was Transformers: Dark Of The Moon in 2011 but has also appeared in TV shows Grey's Anatomy and Private Practice.

Renée Zellweger is reportedly returning in her role as the mishap-prone British publishing executive as she enters her 40s.

The plot is being kept top secret but the title of the film - Bridget Jones's Baby - does offer a major clue.

The story is understood to be based on columns written by creator Helen Fielding and not her latest novel, Mad About The Boy - in which Bridget has a couple of children and Colin Firth's character has died.