MRS. DOUBTFIRE (Directed by Chris Columbus. Staring Robin Williams, Sally Field, Pierce Brosnan, Harvey Fierstein, Robert Prosky)

WHAT DO you do with Robin Williams? Clearly the funniest man in the known universe, his explosive, improvisational talent is not necessarily well suited to the medium of film, where pre-planning is of the essence and plot a priority. By common consent, his most successful movie performance to date is as a cartoon character. In improvisation, he gave Walt Disney some forty hours of comic schtick out of which they created the Genie that propelled the film Aladdin to blockbuster status. (They subsequently fell out over money, however. “Now I know why the mouse only has four fingers. So he can’t pick up the cheque,” Williams recently commented.)

Williams plays Mrs Doubtfire as a cartoon character, an opera singing first cousin of Tweetie Pie, pursued by a Cary Grant-like Sylvester. The voices are provided by Williams as Daniel Hillard, a struggling actor who had a similar falling out with his employer, stalking out of the recording because they insist he sticks to the script.

In his first self-produced film, Williams has wisely given himself a character that allows him maximum flexibility, a riotous comedian whose skill is verbal agility and whose only flaw is his lack of seriousness. Director Chris Columbus, who oversaw the technically impressive slapstick of both Home Alones, has the sense to stand back and let the humour come to him, jump cutting several times through entire repertoires of impersonations and generally taking every opportunity to let his star fly off the handle.

The premise is as simple as it is ludicrous: faced with divorce and separation from his children, Hillard disguises himself as an elderly woman and applies for a job as their nanny. It is odd that a man so hairy would choose to play a woman, and, despite the best that Hollywood prosthetics can do, not entirely convincing. No one in the movie appears to notice that Williams looks more like a monster with a plastic head than a sweet little old lady, but he suspends belief with his sheer comic brio. It is a characterisation that is absurd enough to entertain children and knowing enough to amuse adults, with more than a touch of Dame Edna (picking up four frozen pork chops from the fridge, she sighs “As I hold this cold meat I’m reminded of Winston, my late husband”).

At its best, Mrs Doubtfire is the funniest Williams has been on screen. It is also, almost inevitably, immensely sentimental. Williams has always prevaricated between pyrotechnical satire and tearjerking mush. Here he manages it not only in the same film but often in the same scene. To be fair, the subject matter – the effect of divorce on children and parents – is clearly close to his own heart and consequently receives a more thoughtful approach than it normally would in a family movie. This is not a saga about the reunion of battling parents, but a tale in which they both must come to terms with each other and their kids. With its sense of loss and undercurrent of desperation, together with the everpresent violins, the experience can be like fighting your way through an emotional battlefield, until you’re not sure whether you’re crying with laughter or sorrow.