Harry Potter and the Half-Blood Prince: great special effects, shame about the non-story

The Harry Potter films resemble creaky old biblical epics in more ways than one. Like The Ten Commandments and The Greatest Story Every Told, the JK Rowling adaptations are stupefyingly long and bum-numbingly boring. They also have a lot to do with miracles and feature more than a few elderly men in long beards. More interestingly, both genres are aimed almost exclusively at punters who have read (indeed, often memorised) the source material.

When the latest film was screened for a select audience earlier this year, the main complaints on internet boards were not to do with the narrative structure (barely present), the lead performances (consistently ordinary) or the special effects (rather lovely, to be fair). No. Every second post whinged that it wasn't exactly the same as the book. Imagine the response of the faithful if, when making King of Kings, Nicholas Ray had left out the Sermon on the Mount and you may grasp the tenor of the acolytes' fury.

So, we can't really judge a Harry Potter film the way we judge a Lars von Trier folly or a Quentin Tarantino entertainment. Harry Potter and Whatever It's Called This Yearis more of a hugely expensive Passion Play than a conventional family entertainment. As such, it must grudgingly be considered a kind of success.

Since the first picture emerged eight years ago, Warner Brothers has made a point of hiring only the finest character actors and the best post-production staff. Okay, two of the three lead actors are somewhat underwhelming (Rupert Grint is the only one who really shines) and the choice of directors has been erratic, but the producers have given Rowling’s increasingly unfocused novels the most thorough of mummifications.

All of which is a way of delaying the inevitable business of finding something specific to say about (reviewer hastily checks notes) Harry Potter and the Half-Blood Prince. Well, it starts with one of the best special effects sequences yet seen in the series. Before you have had time to open your popcorn, a series of scurrying Death Eaters have descended upon London, sped along Shaftesbury Avenue, reached the river and chewed the Millennium Bridge into scrap iron.

When all that chaos has died down, we join Harry, now practically middle-aged, as he flirts with a pretty girl at a train station. Later, Michael Gambon’s fruity Dumbledore seeks out an old colleague played by – can he really not have appeared before? – a reliably eccentric Jim Broadbent.

These opening parries offer Potter agnostics the prospect of something a little less creaky than the earlier episodes. But, when the kids eventually arrive at Hogwarts, the film settles down into the usual morass of whacky potions in twisty bottles, teachers with names such as Whackford Oblongbottom, and furtive snogs beneath the Quidditch bleachers.

The three main actors (the owlish Daniel Radcliffe and the lightweight Emma Watson join Mr Grint yet again) work hard at distracting attention from their conspicuous superannuation, and the teachers continue to relish their well-paid vacations from the Royal Shakespeare Company.

The film will, in short, satisfy most folk who enjoyed the earlier episodes. The unconvinced may, however, find one question echoing in their minds throughout: where’s the bleeding story? Quite a lot happens in the latest episode, but, if asked what the film is about, you would have some trouble offering any kind of concise answer.

Well, it’s about an attempt to discover facts concerning Lord Voldemort’s childhood. It’s about Harry’s affection for Ron’s sister. It’s about two-and-a-half hours long. (Thanks to Bob Dylan for that joke.)

Still, you would have similar difficulty summarising the plot of the source material for The Ten Commandments and The Greatest Story Ever Told. At least the Almighty's ghostwriters managed to limit their epic to just two volumes, whereas the seventh and eighth Harry Potter films are still to come.