FILM / Nanny who came in from the cold

It must be perverse to say this of a lady of undisputed avoirdupois, but Mrs Doubtfire, in Mrs Doubtfire (12), is a lightweight creation that could have done with a shade more flesh on her bones. Not that the disguise - which Williams, an out-of-work, divorced actor adopts to spend more time with his kids - isn't a brilliant feat of mimicry. But there's not much dramatic mileage in the old girl.

In Tootsie, the film to which this will be compared, Dustin Hoffman was a brash, belligerent character who learnt from his female persona. But here Williams' male - as in Williams movies passim - is already a caring type: the perfect mom in all but a detail. Odd that in a film showcasing his talent, his character is the blurriest, least satisfying element of the story.

He has no background, no past - early on he visits his brother, the flamboyant Harvey Fierstein, a figure shamelessly shoehorned into the plot to help Williams into his latex; then he's dumped, never to be seen again. And a frisson of psychology shudders briefly when Fierstein tells his brother in drag, 'Any closer and you'd be mom.' But the soft-brogued Scottish Euphegenia Doubtfire seems somehow a bit implausible as their joint matriarch.

The other characters seem sharper: Williams' estranged wife (Sally Field) starts out like the nasty, spoilsport career mom. She's at eternal loggerheads with Williams, a dad who wears his baseball cap sideways and throws his kids the best birthday party ever, which musses her perfect home - typically, she's an interior designer.

Except that Field then expostulates: 'Why do you always make me out to be the heavy?' and you see how the way Williams indulges his kids can also be a subtle form of getting at her. At the end, she realises she has been able to delegate housekeeping to Williams as a woman, as she could not to him as a man. The device allows her to accept an unconventional arrangement.

The director, Chris Columbus, has swung from hip cynicism (Gremlins) to arch-conservatism (the Home Alone films), but this is Hollywood liberalism in full flow: Field has a new boyfriend (Pierce Brosnan) and the story signs point to a wolf in sheep's clothing whom Mrs Doubtfire will see off, tail between legs. But, no, the button remains unpushed and the marriage unmended, even if the film can't resist pressing the point in a ghastly little homily. It's a film without fall guys.

That's not to say that there isn't some subtle aggression. Mrs D's floral flock is licenced to say things that, in mufti, would earn the speaker a fat punch on the nose. The rivals' verbal sparring has a wicked edge and when s/he performs the Heimlich Manoeuvre on Brosnan it looks like an obscene act. Other scenes have a touch of Dame Edna's Neighbourhood Watch, of sugary compliments thinly veiling malice 'What a delightful cubby' s/he twitters at Fields' immaculately ordered kitchen. 'I'm surprised there isn't a little label saying 'spoons'.' If you could detect any development in Williams' character, it is that Mrs D teaches him regularly to change his socks.

'How about Joan Collins?' asks Fierstein, as Williams tries out a range of female personae. 'Ach, I don't think I have the strength,' he sighs, with some regret. But fortunately the imitable genuine article is on display elsewhere in the film of Steven Berkoff's Decadence (15). This is a rum affair, an excoriation of Eighties greed and excess that staggers from stage to screen several years too late to be effective.

Berkoff plays a grotesque upper-class toff (socially mobile, but we're not sure in which direction, nouveau riche or declasse), Collins is his mistress and also his abandoned wife who has taken out a contract on him (Berkoff appears again as the yobbish hitman). Curiously, having set this plot in motion, he proceeds to ignore it completely: the hit never comes near fruition and, indeed, the rough couple gradually fades from the story.

Berkoff makes few concessions to the film form: many scenes play as long monologues to camera; the movement is highly-choreographed, with extras freezing in tableaux vivants or twirling around in elaborate pirouettes. Meanwhile Collins, a national asset the British cinema should make more use of, conveys, with a cunningly pursed lip and a raised eyebrow, more than Berkoff can from a burst of serial vomiting and a delivery pitched to the back of the upper circle. It's a textbook lesson in the difference between stage and screen acting.