The new building, which is actually in Swiss Cottage rather than Hampstead, has been eight years in the making. It replaces a 40-year-old Portakabin, where talents as diverse as John Malkovich, Martin Clunes and Ewan McGregor have performed. Supportive of new writing, the theatre has incubated Mike Leigh's masterpiece of suburban loathing, Abigail's Party, and early work by Stephen Poliakoff.