Improvisation has become an indispensable tool in postwar theatre. It is accepted as a valuable method for actors to explore both the ‘inner truth’ of a character and the world of the play when interpreting text-based drama. It is also increasingly recognized, and used, as a technique which actively produces innovative dramatic material. The concept of the rehearsal room as a creatively productive play-room has been legitimized during the postwar period. Improvisation workshops and devising are the basis of work in community theatre and physical theatre, and are also considered an essential component ofdrama in education at all levels. Two manuals which have had a huge impact on the teaching and practice of drama are Keith Johnstone’s Impro and Clive Barker’s Theatre Games. Following Theatre Workshop’s Oh What a Lovely War, improvising around research materials has become the staple method of TIE (theatre in education) companies and those producing ‘documentary drama’ and ‘heritage drama’, where the play is evolved and is structured through the rehearsal process. In alternative theatre, Monstrous Regiment and Joint Stock developed influential methods of working with actors and playwrights together, where the issues and ideas of a play were explored first through improvisation before the writer shaped and structured a playtext (for example, Churchill’s Vinegar Tom and Cloud 9, which are both remarkably unconventional in form).

Mike Leigh has refined a method of working in private improvisation with actors on his characters, before allowing them to meet and improvise situations which he eventually structures into a play. His work owes much to the ‘naturalistic’ tradition and the results are recognizable ‘plays’, which may be why his work transfers so well to the screen. The ‘collective commitment’ that informs theatre produced through improvisation is indicative of the way the anti-star and anti-director system has evolved in alternative theatre, where ensemble practice in the cornerstone. A large number of companies work through collaborative methods rooted in improvisation to make their work, sometimes using a text as a springboard or starting point (Volcano’s Ibsenities), incorporating autobiographical material (Forced Entertainment), or employing visual or design motifs (The People Show). This is not merely evidence of postmodernism in theatre but a move towards acknowledging the power of the actor as a creative initiator, and demonstrates a late twentieth-century shift in emphasis from the ‘actor as interpreter’ to the ‘actor as creator’.