Sugar-sweet and selling like hot cakes, the unlikeliest hit of the year

It is the best-selling phenomenon you may never have heard of. But if you haven't, it's a sure bet you're not a parent.

For High School Musical, a sugar-sweet tale of classroom rivalries, is the buzz of British playgrounds. It has topped the DVD charts with sales of more than 400,000 so far and is likely to be in a quarter of all households with the target audience of six to 11-year-olds by Christmas.

Although it has not been released in cinemas and will only get its terrestrial television premiere in Britain on BBC1 next week, its first week DVD sales were bigger than television hits such as The Office.

It has become the fastest-selling television film on DVD in the UK with Official Charts Company figures showing that only big screen blockbusters such as Pirates of the Caribbean are doing better. The accompanying soundtrack sold 650,000 copies in its first 10 days on release.

Anthony Peet, the managing director of Buena Vista Home Entertainment, which released the DVD, said it was being snapped up for presents. "To borrow one of the movie's most popular songs, UK parents have clearly got their head in the game and are very tuned in to what every kids wants this Christmas," he said.

Sam Robinson, the editor of Girl Talk magazine, which is aimed at the pre-teen market, said she knew it was going to be a success in the UK because of its performance in the US, where it set ratings records for the Disney Channel and has been watched by 37 million viewers with repeat showings since it premiered last January. The soundtrack is the biggest selling CD this year to date and has produced six hit singles.

The film began regular screenings on the Disney Channel in Britain in September and the magazine immediately received feedback. "Everybody was already talking about it, even though it was only on a cable channel, which is unheard of. It's just at the point now where it's about to go bananas and everybody can't get enough of it," Ms Robinson said.

Since October, there has been a High School Musical story in every fortnightly edition; the current issue includes a sticker album and in January, Girl Talk will include the words to all the songs. Magazines such as Top of the Pops, for slightly older children, have also been featuring the film regularly.

With a storyline that is part Grease, part Fame, High School Musical features Zac Efron as the basketball captain, Troy, and Vanessa Anne Hudgens as the shy, studious Gabriella. Ms Robinson said: "To me, on a personal level, it's very cheesy, sugary-sweet, but to our readers that's part of the appeal. It's so safe, it's got a happy ending and it's all about belonging and that there's a place for everybody."

Younger girls of eight or nine wanted to know they can be part of the gang, Ms Robinson said. But the film was also a hit with teenagers because of the element of romance. "It works in a way I've never seen anything work before with everyone from eight-year-olds to 15-year-olds. It's unbelievable," she said. "It says whatever sort of boy or girl you are, you can be cool and popular. You can be the person you want to be. It's so lovely, it's very heartening. You just assume that teenagers want things that are a bit more edgy like Little Britain, but they don't really."

The Disney Channel is already planning a sequel for the summer in which the leads will reprise their roles. High School Musical cost Disney £2m to make and it won two Emmy awards.

The plot

Troy Bolton, the school's basketball captain, and Gabriella Montez, a gorgeous bookworm, meet at a New Year's Eve party. When school starts, Troy discovers Gabriella is a new student, but their friendship irritates people at school. Eventually, all come to agree you can be whatever you want to be. There's a very happy ending.