Jamie Dornan says filming '50 Shades of Grey' has improved his walking.

The 31-year-old actor has been cast as sadomasochistic millionaire Christian Grey in the film adaptation of E L James' erotic novel and had to shoot a ballroom dancing scene which inadvertently made his day-to-day posture better.

He explained: ''So basically, I've always had a complex with the way I walk. I've not always been told I've got a bad walk, but someone's always commented on my walk. It's always been a bit like, 'All right. That's how you walk?'

''My wife tried to help by making me lean back and then in 'Fifty Shades...' my character has to dance the foxtrot and the teacher said, 'Do it as though you are walking, heel to toe.'

''No one had ever told me that. I was always toe-to-more-toe! Now I just apply that every day, when I'm walking around.''

Jamie - who is married to Amelia Warner - insists the movie will be a success even if just a small percent of those who read the book enjoy the film.

Talking on 'The Graham Norton Show', he said: ''I mean, look, we're in a really powerful position that 90-plus million people have read the book so if like a third - I mean, a hundredth of those people - that's successful if they go see the film.

''It's a nice position to be in, but I have no idea what it's going to do.''

Jamie stars opposite Dakota Johnson, who plays Christian's lover Anastasia Steele, in the movie.