Olivia Colman
I love this actress - since she came to national attention as "Bev" in the AA car insurance advert! ("We used to have one of those" *wiggles nose*). It's a travesty they replaced her - then again she probably outgrew the role.
Since then she's done great work in Green Wing (with Stephen Mangan), Peep Show (with Robert Webb) etc.
The trailer caught me completely by surprise! She's NAKED! In a 12-rated trailer! Proper naked! I couldn't concentrate on the first hour of the movie after that.
Its nice to see name actors taking on naturist characters in a mainstream movie - I hope they are portrayed relatively sympathetically, naturism is too much fun to just be mocked and laughed at all the time. And hopefully it won't have a bad effect on their careers - it didn't hurt Alexander Armstrong, Ben Miller or Green Wing co-star Sarah Alexander when they appeared naked in Armstrong & Miller a decade ago.