If you aren’t aware of the phenomenon that is High School Musical, it’s a safe bet that you’re over the age of 15 and don’t yet have any children or grandchildren under that age. For its target demographic – mostly girls in their “tweens” (roughly 8-14) – High School Musical is like Harry Potter, Barbie and Pokémon all mixed together and combined with a serious sugar rush. It seems that they just can’t get enough of this wholesome franchise of sickly-sweet, unbelievably innocent films, where pristine teenagers sing and dance about the joys of young love, close friendship, and being true to yourself.

With such themes at its heart, you can probably guess which company masterminded this new form of kiddie catnip – yep, good old Disney. It’s yet another re-jigging of the tried and tested Disney themes that we’ve seen countless times down the years – only this time successfully updated for the modern age.

Perhaps it’s an indication of Disney’s own loss of confidence in the relevance of its old product that the first High School Musical movie, which only came out less than three years ago, was never intended for the big screen. That’s right – the original film was a TV movie, made for the Disney Channel and first screened back in January 2006. Disney, it seemed, had been reading too many tabloid newspaper tales of feral youngsters roaming the streets in gangs, getting in fights, smoking, drinking, having underage sex, and generally going to the dogs. Surely the children of today wouldn’t be interested in anything as old-fashioned and uncool as Disney’s traditional brand of family values and decency?

Well, Disney was wrong. The film pulled in an impressive 7.7 million viewers for its premiere, despite only being available on cable TV. By the end of the year, it had been shown repeatedly on the Disney Channel worldwide, even making it on to the BBC during the key Christmas season, winning over legions of new British fans, while its soundtrack became the best-selling album of the year in the US in 2006. Somehow the old Disney magic had returned without them even realizing it. DVD sales, in turn, were immense – with 1.2 million copies sold in its first six days, the first set a sales record.

And so, in the last three years, High School Musical has snowballed. A concert tour of the Americas was running by the end of 2006, there were numerous singles released, a stage play version, a version done on ice, swiftly followed by a TV movie sequel (which has in turn spawned a stage play), not to mention the six computer games and countless books and other bits of merchandise that the franchise has spawned to date. Not bad for a film whose budget was only $4.2 million.

In other words, it was only a matter of time before the phenomenon hit the big screen – and now, with the third movie, it has. The only odd thing is that the cast – and characters – are now getting a bit old for High School, so this latest outing revolves around their hopes and fears for the future as they approach their move to university. How to deal with such worries? Why – let’s put on a show! It’s hardly original, but fans of the series are unlikely to care. And though it would be easy to criticise a film that’s so sickly sweet and, well, nice, let’s face it – if they enjoy it, why not let the kids maintain their innocence while they can? Rather this than all the sex and violence that’s so endemic everywhere else.