Colin Firth's Mamma Mia pride

Colin Firth believes starring in 'Mamma Mia' is one of the "best things" he has ever done.

The British actor - who has won the Best Actor awards at both the Golden Globes and the BAFTAs this year for his role as King George IV in 'The King's Speech' - explained while people expect him to be ashamed of his all-singing all-dancing role in the musical film, he counts it as one of his biggest achievements.

He said: "I think it is one of the best things I have ever done. People expect me to be apologetic about it but I'm not.

Right now I would say there's three things of which I am most proud, 'A Single Man', 'The King's Speech' and 'Mamma Mia'."

The 50-year-old star also joked that it didn't take much persuasion for him to appear as Harry Bright in 'Mamma Mia' because he is a "drag queen" with "no shame".

Colin added to CBS show '60 Minutes': "That may be the reason I did it. I have no shame. I am such a drag queen, it's one of my primary driving forces in life. You cannot dangle a spandex suit and mascara in front of me and not expect me to go weak at the knees."