Before the screening began, the PR stood up and asked reviewers to “preserve the fun for fans” and not give away the plot. Of course, not all of you will be fans of the zeitgeisty HBO series, which ran for six years and has now spawned Michael Patrick King’s feature-length comedy romance; still, I’ll see what I can do.

Here is a list of things that may or may not occur: marriage; birth; infidelity; Marxist-Leninist debate on the redistribution of wealth. Suffice to say, if you’re expecting surprises — don’t. Which is not to say that Sex and the City is a chore. Reader, I liked it quite a lot.

The film begins with all four friends alive and kicking. Three of them are in their forties and Samantha is about to hit 50 — but you wouldn’t guess it. New York looks gorgeous and fabulous/ludicrous outfits abound. With a new book about love in the works, Carrie (Sarah Jessica Parker) is planning a Big wedding to Mr Big. Meanwhile, Charlotte (Kristin Davis) is busy with her adopted Chinese daughter and Samantha (Kim Cattrall) is in LA with her loyal hunk.

As for stressed working mother Miranda (Cynthia Nixon) — well, she’s the one who gets the first bit of bad news. Her “problem” spills into Carrie’s life and ... to cut a top-secret synopsis short, the pals wind up in Mexico, where, among other things, Charlotte “shits” in her pants. Their word, not mine. Like most HBO shows, SATC was famous for its deployment of “adults-only” language and King (who worked on the series from the beginning) has wisely kept the dialogue salty.

Even as we’re encouraged to covet the spending-power and privilege of these characters we’re invited to giggle at their fear of the real world. Charlotte is so terrified of catching something in Mexico (even though they’re in a five-star resort) that she’ll only eat puddings shipped in from Poughkeepsie. Yet it’s she, of course, who gets the funny tummy. She is too anal for her own good.

Similarly, when Samantha tries to live out a sexual fantasy (she lies on the kitchen table covered in home-made sushi) things do not go according to plan. WASP-y perfection, exotic perfection — all such sterile facades are doomed.

The above scenes are flat-out funny; think Woody Allen meets the Farrelly brothers. And Davis and Cattrall are natural comediennes. It’s also nice to see Miranda, the most obviously feminist character of the foursome, playing a dominant part in the proceedings. In the second half she and Carrie — united by disaster — become so close that they’re mistaken for lovers.

True, the script’s daring is a little schizophrenic. Miranda, on the hunt for a new flat in an “ethnic” part of town, spots a white man with a baby and says: “Follow him!” We’re supposed to get that this is ironic — she’s not being racist, she’s just acknowledging that neighbourhoods become desirable when whites move in. But there’s a fine line between ironic and smug, and the film totters back and forth across it. Carrie’s new assistant — the supremely efficient Louise (Jennifer Hudson) — is black. Poor but happy, permanently grateful and a big fan of white movies (she buys Carrie a DVD of Meet Me in St Louis) she’s a dream come true for guilty liberals. Hudson, star of Dreamgirls, is a pro and almost makes the schmaltz work. But not quite.

SATC is full of such contradictions. It’s fine to see two gay men kissing, yet when a cross-dresser applies for the role of Carrie’s assistant, it’s taken as read that he’s a no-no for the job.

There is also a hilarious moment where the women take a miserable Samantha to task for drowning her sorrows in food (“What’s with the gut?”). Carrie and Miranda drink like fish when they’re down. Clearly, comfort drinking is fine but comfort eating is psychotic.

The financial clout of these women is considerable (think of it as the Princess Pound), yet economic realities are occasionally allowed to intrude. A magazine on Carrie’s floor asks: “How long before the real-estate bubble pops?” Carrie, typically, reaches instead for Vogue.

The decadence can be overwhelming. What keeps you going is Sarah Jessica Parker, though not for the reasons you might think. She’s the least talented of the four actresses. What she has is a fascinating presence. Parker wears size 0 clothes; her nose and chin, though, remain obstinately XL. She also has a mole on her chin, tired, tiny eyes and bony limbs. Cinderella? Most of the time, her Carrie looks more like the wicked stepmother. The great thing about the movie is that it acknowledges the shortfall.

This isn’ t the kind of Barbra Streisand vanity project where everyone tells the heroine how beautiful she is every 30 seconds. When the Vogue editor offers Carrie the chance to be photographed in a range of designer wedding dresses she purrs: “Just think, Carrie. Vogue photographers, Vogue air-brushing ...”

Carrie isn’t the most beautiful woman in the world; she’s not even young. Yet, crucially, she is loved.

Back on planet Earth, weird-looking women of a certain age face rather more rejection. As fantasies go, however, the one wrapped up in a bow in SATC is pretty pleasurable. If an actress like Julia Roberts was playing Carrie, the film would resemble a thousand other “modern” fairy tales. With SJP in the lead, it really is a one-off — not vintage material, perhaps, but definitely worth trying on for size.