Firth thanked the team behind the film, including a reference to his "masterly voice coach Neil Swain" while accepting his Leading Actor Award.

BBC: King's Speech voice coach 'proud' of Firth's stammer

Affleck was also nominated for the Leading Actor award, but that prize went to Daniel Day-Lewis, the favorite not only of the bookies but of his peers, including fellow nominee Hugh Jackman.

CNN: 'Argo,' Affleck take top prizes at BAFTAs

He won the Laurence Olivier Award for best actor, the Drama Desk Award for outstanding actor in a play, the Outer Critics Circle Award for best featured actor in a play, and a Tony Award for best performance by a leading actor in a play.

BBC: Obituary: Richard Griffiths

Hollywood star Kevin Kline picked up the award for outstanding actor in a play for his leading role in Cyrano de Bergerac, opposite Jennifer Garner.

BBC: US critics give Broadway honours