If anyone has any doubts that James Stewart was the consummate film actor, his performance as Elwood P Dowd in this classic comedy of the Fifties will dispel them.

Here is a 42-year-old bachelor, living in a large, comfortable house with his sister Veta (Josephine Hull) and niece Myrtle Mae (Victoria Horne). He is exceptionally friendly and polite and spends his time frequenting bars, talking to strangers, whom Veta would consider "riff raff", and inviting them home to dinner.

She is at her wits end, because having such an eccentric brother - some would call him loony - around the house when she is entertaining the smartest ladies in town causes palpitations. After one embarrassing incident, when his antics emptied the drawing room, Myrtle Mae rushes upstairs in a state, squealing, "I'm going to lose myself in a strange city! I'm going to change my name!"

The problem with Elwood is not his generosity of spirit, child-like innocence, or refusal to see wickedness in anyone, but his friend and constant companion, an invisible 6'3'' ("to be precise") white rabbit, called Harvey.

Based on the Pulitzer prize winning play by Mary Chase, the film retains many theatrical devices, such as the timing of entrances and departures, misunderstandings and mistaken identities, farcical incidents (Veta being manhandled upstairs to the "crazies" wing at a posh mental home when she has come to have Elwood sectioned) and unexpected romances (the repressed, gawky Myrtle Mae with Wilson, the rough, mannerless male nurse). The writing is consistently witty, making full use of a splendid array of secondary characters.

Hull practically steals the film. Tiny, brisk, expressive and permanently harassed, she is nothing less than hilarious. However, Stewart's ability to make this embarrassing fellow Elwood, who talks to himself - sorry, Harvey - a sympathetic, genuine person, with a heart of gold ("My mother taught me that in life you must be oh so smart, or oh so pleasant. I recommend pleasant") and a discreet drinking problem, is a lesson in the subtlety of the thespian's craft.