A British film starring Liam Neeson, Hugh Grant, Emma Thompson, Colin Firth, Martine McCutcheon, Rowan Atkinson, Billy Bob Thornton, Alan Rickman, Keira Knightly, Martin Freeman, Andrew Lincoln and Kris Marshall - phew! - is being tipped as an all-time success to top such hits as Four Weddings and a Funeral, Notting Hill, Bean and Bridget Jones's Diary.