Director Nicholas Hytner brings Alan Bennett’s London and Broadway smash to the screen with the original stage actors and brings out the frisky best in all of them. Set in 1983, the story concerns eight students at a Yorkshire school being pressured to get into elite universities. The pragmatic Mr. Irwin (an A-plus for Stephen Campbell Moore) sees passing the entrance exams as performance art. Hector (Richard Griffiths), the general-studies teacher, puts the emphasis on learning — that is, when he’s not teasing the boys in class or copping a feel on his motorcycle. Griffiths, an actor of expansive girth and talent, is a dynamo who finds every shade of humor and heartbreak in the role. He’s especially poignant in his scenes with Samuel Barnett, as a gay misfit who pines for Dominic Cooper’s straight object of lust for wankers. Cooper and Barnett are in the making, and Frances de la Tour as the grande dame fed up with teaching “centuries of masculine ineptitude” is a droll, dazzling wonder. The film can’t hide its stage origins, and in cutting almost an hour on the journey from stage to screen some resonance is lost. But Bennett’s dialogue sparkles and skewers with killer wit. Dig in.