The Boy Friend (1971)

The assistant stage manager of a small-time theatrical company (Polly Browne) is forced to understudy for the leading lady (Rita) at a matinée performance at which an illustrious Hollywood director (Cecil B. DeThrill) is in the audience scouting for actors to be in his latest "all-talking, all-dancing, all-singing" extravaganza. Polly also happens to fall in love with the leading man (Tony) and imagines several fabulous fantasy sequences in which the director is free to exercise his capacity for over-the-top visuals in this charming 1920's era flick.