For all his versatility as a writer-director, I was surprised to learn that Mike Leigh (Secrets & Lies) had made a film about the genesis of Gilbert and Sullivan’s mid-1880s comic opera The Mikado. Yet this 160-minute “backstage musical” is about something he knows intimately—the complex of personal, organizational, artistic, and cultural factors that go into putting on a show. Leigh begins with leisurely character sketches of composer Arthur Sullivan (Allan Corduner) and librettist William Gilbert (Jim Broadbent), two very different men whose collaboration appears to be at an end. Only after Gilbert’s wife (Lesley Manville) drags him to a Japanese exhibition in London does The Mikado (and this movie) begin to take shape, and after that the film keeps getting better and better. The actors and actresses in the stage production, including Leigh regular Timothy Spall, all sing in their own voices, and Leigh’s flair for comedy and sense of social interaction shine as he shows all the ingredients in The Mikado beginning to mesh. Thoroughly researched and unobtrusively upholstered, this beautifully assured entertainment about Victorian England is a string of delights. With Ron Cook, Wendy Nottingham, Eleanor David, Kevin McKidd, Shirley Henderson, Dorothy Atkinson, and many Leigh standbys, including Alison Steadman and Katrin Cartlidge.