The brilliant Irish comedian Andrew Maxwell describes doing stand-up at the Edinburgh Fringe as ‘exams for clowns’, and even though I first appeared there in 1981 (when the Cambridge Footlights Revue featured Hugh Laurie, Stephen Fry, Emma Thompson and Tony Slattery), I felt an overwhelming surge of nervousness as I began my short run this year with the peerless mimic Jan Ravens (who herself had directed that illustrious 1981 cast).