Christopher Cook (in the Chair) talks with Peter Kemp Sheridan Morley and Marina Warner. This week's subjects: ScreenPlay: Between the Cracks by Lucy Parker and Lennie James (BBC2 last Wednesday): Bussy D 'Ambois by George Chapman at the Old Vie. London; The Letters of Max Beerbohm edited by Rupert Hart-Davis ; the L.S. Lowry centenary exhibition at the Barbican Art Gallery, London: Chris Menges 'sfilm.A World Apart. Producer PHILIP FRENCH