The pop industry's most fiendishly lucrative masterstroke, after The Jacksons and The Osmonds, was realising that boy bands don't need to be family-based, so there's no imperative to accommodate members who are too old, too ugly or too talentless.
In the case of One Direction, two out of three ain't bad. They're young (17-20), and four-fifths of them are very cute. But talented? Assembled in 2010 on a brainwave from guest X Factor judge Nicole Scherzinger (if you're a gullible idiot), or preconceived at a Talkback/Fremantle/Syco production meeting (if you're not), the five band members were – rightly – considered not good enough singers to be solo competitors. They can't dance either.
None of which matters. One Direction don't exist to sell albums. They exist to sell calendars: in December, Amazon.co.uk announced that the One Direction 2012 was their biggest-selling celebrity calendar of all time.
Tonight, the boys almost literally step out of a pin-up poster magazine. In inane introductory profiles we learn that, for example, Harry likes crispy rolls and girls, and dislikes beetroot. This is greeted with ear-splitting screams from the 99.9 per cent female audience.
There is, you see, a One Direction pecking order, and empirical research provides me with the following findings: moptopped Harry Styles is by far the most popular. Close your eyes and guess when Harry's on lead, from the spike in decibels. You'll never be wrong. Next, by some distance, is Zayn Malik, after which Louis Tomlinson and Liam Payne are neck and neck for third, and last is the Bez of the band, Niall Horan.
Famously, when The Beatles played stadiums, the Sixties' PA systems weren't able to drown out the screams. With One Direction, it's a blessing. Their own material, padded out with covers of Black Eyed Peas and Kings of Leon hits, among others, consists of jingles rather than songs, easy to sing along to and instantly forgettable.
However, 1D's fanbase of tweenagers are having the most intense experience of their lives so far, and who would begrudge them that? It won't be long before they find out that real teenage boys can only disappoint them.
What they're presented with is a high-life fantasy. We see the guys on skateboards and snowboards, larking around skiing, and, insidiously, attending the fictional but clearly super-posh Webberley College. Where's Malcolm McDowell on the rooftop with a Bren gun when you need him?
The only way The Risk will ever sell calendars in significant quantities is if they all get Christmas jobs at their local HMV. In case you've forgotten them already, The Risk (eliminated in Week five) are the boy band cobbled together by judge/mentor Tulisa Contostavlos (again, if you're an idiot).
A local radio jock, hosting the showcase, wants to know, "Who cried when The Risk left X Factor?", and even the children's whoops sound ironic. Already doomed, Charlie Healy, Andy Merry, Derry Mensah and Ashford Campbell amble onstage. After passable karaoke renditions of Plan B's "She Said", Take That's "Greatest Day" and Shalamar's "Night to Remember", all four come to the barrier to be molested by hands too young even to touch a cigarette. Lap it up, lads. It won't last.
Next up? In a bowler hat and long, straightened red hair, looking like a Clockwork Cher, it's Janet Devlin. A teenage warbler whose cutesy "Oi'm only a little Oirish pixie" act became more grating with every passing week.
An early favourite, she blew it all by repeatedly forgetting her words, and finished fifth. Fittingly, her first song tonight is "Forget You". She has a dreary stab at Rihanna's "We Found Love", and says: "I'm sorry about all the sad songs, but it's kind of my forte."
Then she sings Adele's "Someone Like You" – and forgets one of the lines. I can't abide Adele, but even I could sing "Someone Like You" in my sleep, purely by osmosis. Further proof that if singing sad songs is Janet Devlin's forte, remembering the words to them is her debole.
Simon expands his horizons at Hofesh Schechter and Antony Gormley's music-and-art spectacular, Survivor
Laetitia Sadier, lead singer of Stereolab and side-project Monade, performs material from her recent solo album The Trip at the Green Door Store, Brighton (Fri). Meanwhile, reunited Britpop hitmakers Dodgy trail their imminent fifth album, Stand Upright In a Cool Place, at the Arlington Arts Centre, Newbury (Wed) and Artrix, Bromsgrove (Thu).