Cameron Mackintosh is building a new theatre. “The 500-seat Sondheim will be the first new theatre in Shaftesbury Avenue in more than 70 years. Not that you will be able to guess. The truly clever, if controversial design led by the husband-and-wife architect team of Nick Thompson and Clare Ferraby, of RHWL Architects’ Arts Team, will join the existing Gielgud and Queen’s theatres at their Edwardian hips.”