Billy Connolly and Tom Courtenay tackle opera in Quartet

Two of the stars of Quartet have spoken of the challenges of learning to sing opera for their roles, and of their experience working with Dustin Hoffman on his directorial debut.

Billy Connolly and Tom Courtenay star alongside Dame Maggie Smith and Pauline Collins in the story of a home for retired musicians.

Connolly and Courtenay told BBC Breakfast that Hoffman was "moved" when he saw their first performance.

Clip of Quartet courtesy of Momentum Pictures