KYLIE, Madonna, young Spice Girls, Whitney and even Mariah have done it, and oops, Britney's done it too, crossing over from frothy pop to movie candyfloss.

The one-time Broadway starlet who became the world's biggest teen pop star on the strength of one college fantasy video has made the inevitable step to Hollywood babe, with funding from her record company: the ultimate in cynical product placement.

Britney's movie debut is a coming-of-age road movie aimed shamelessly at the very age group and girl pack she sent into tantrums with her late-arrival and no-autograph performance at the London premiere on Monday, although male students and ancient raincoat devotees will be thrilled by the opening sight of a bronzed Miss Spears bouncing about in bra and panties, miming to her favourite Madonna record as she dreams of pop stardom.

Like Mariah Carey in last year's career-crashing Glitter, Britney is not stretched in the role of a teenage singer, but whereas poor Mariah made her movie debut on the crest of a spectacular slump, Britney's sense of timing is perfect - and certainly better than on Monday when the boos rang out.

We know from her infamous schoolgirl video that she has a screen presence to go with the Barbie looks but here, in a squeaky clean role as pure and doe-eyed as Bambi, she copes competently with her acting brief and acting in briefs.

Britney is Lucy, who goes on a road trip to LA in yellow dress and pink cardie with her lifetime friends Kit and Mimi (Zoe Saldana, Taryn Manning) and their handsome driver, moody musician Ben (Anson Mount, surely a porn name!). High school over, Lucy wants to escape her over-protective father (Dan Aykroyd) to meet the mom who deserted her (Kim Cattrall, from Sex In The City).

Her friends have targets too: Kit plans a surprise visit on her student fianc with marriage in mind; Mimi, pregnant and in need of money, intends to enter a Californian singing contest.

Inevitably, they are in for a (very slightly) bumpy ride, with fall outs, reconciliation and a karaoke bonding session to Joan Jett's I Love Rock'n'Roll, plus plenty of singing along to old hits in the back of the car. Nothing would make a teenage problem page, everything works out for the best, but this particularly buttery popcorn will delight young girls and Britney boys alike. Everyone else should arrive even later than Britney and miss it altogether.

Updated: 08:57 Friday, March 29, 2002