A French Mistress

A French Mistress is a 1960 British comedy film directed by Roy Boulting and starring Cecil Parker, James Robertson Justice, Agns Laurent, Ian Bannen, Raymond Huntley, Irene Handl and Thorley Walters.

A young French woman, Madaleine Lafarge Laurent, is appointed as a French teacher at a rather oldfashioned English public school which is not used to women teachers. She causes a stir and complications ensue.A romance develops between her and the headmasters son Bannen who is also a teacher at the school. The headmaster Parker is concerned as he comes to believe that she is really his daughter, from an affair he had during a holiday in France in his youth. He attempts to stop the romance by sacking her so that she will go back to France, but the boys go on strike and nearly riot. It transpires at the end that there has been a misunderstanding, which means that she cannot be his daughter. ........

Source: Wikipedia