JLS, Brighton Centre, Brighton<br/>Vampire Weekend, Apollo, Manchester

Deltoid-stroking JLS have got the tweenies screaming, even if their stage show wasn't up to much by mega-pop standards

(GETTY IMAGES)

If you could bottle this stuff and sell it, you'd never need to work again. Eau de Hysteria, by Cowell. I've been to a lot of boy-band shows in my time, but nothing quite like this.

Any critic worth their salt needs to step outside their familiar territories once in a while. There are whole gonzo travelogues waiting to be written about this stuff. Fear and Loathing on the Boy Band Trail, 2010. Never mind the inevitable Wembley Stadium show. Now is the moment to catch JLS, on their first- national tour, while they're still a rising pop phenomenon with a rocket up their collective behind.

The sheer shrillness of the screaming is up several notches from anything I've heard in years. You hold your ears in pain, but you just can't help grinning. And the banners are straight outta the heyday of Osmond Mania.

A video montage shows the members and their names in rapid rotation, and it's possible to divine their exact order of popularity. Little Aston Merrygold wins hands down, then it's tall and handsome Marvin, cheery Oritsé and poor JB in last position.

On film, they stroke their own oiled-up deltoids, setting the tone for an incredibly homoerotic show (not quite early Take That standards, but approaching it). Then, to thunderclaps, they appear: four Palitoy action dolls in dark glasses, who one by one take off their shades, beginning what amounts to a show-length slow-mo striptease. During one break, Aston claims to be getting hot and wants to remove his top, flashing his scrawny six pack to chants of "Off! Off! Off!" In sociological terms, this willing submission to the female gaze is almost the only point of interest, other than the fact that they're Britain's first black and mixed-race boy band since the short-lived MN8.

Looking around, I realise something incredible. There are no men here. At all. It crosses one's mind that JLS might be having the wildest time imaginable right now with the small subset of their crowd who are over the age of consent. The music? Who cares. There's nothing to say, except that they make bog-standard R&B, that the line "If I die, would you come to my funeral, would you cry?" is jarringly dark, and that "Everybody in Love" is a terrifyingly effective earworm.

There's no band, the backing being entirely pre-recorded. Indeed, when they do bring out a guitarist, Steve Daley, they make a feature of it. And JLS's singing is competent rather than stunning. In Shai's "If I Ever", their X Factor audition song (and one of numerous covers which pad out the show, including a lengthy Jacko medley), JB can hit the show-stopping high note – "my frieeeend!" – and earns his place in the band for that alone.

The show certainly isn't a spectacular. Some LED staircases, footage of flaming hearts, four ripped vests and four ripped chests. Low budget by mega-pop standards. And the dancing ain't up to much. But they can wear a white tux, carry a red rose and clench a fist of pure emotion, and in this context, that's what counts. If these guys came out as Labour supporters, they could even save Gordon Brown.

"Strokes + Um Bongo ad = first Vampire Weekend album. Strokes + Lilt ad = second Vampire Weekend album." When I Tweeted this verdict a few weeks ago, it went mildly viral, and the amount of RTs it received suggested I'd tapped into a residual frustration with the New Yorkers' indie-meets-world music shtick.

Sometimes though, you feel like a killjoy for tutting at what 2,000 18-year-olds are jumping up and down to, from "A-Punk" to "Cousins" and all points in between. It would just be nice if they were jumping around to something which had moved on marginally from The Housemartins.

Ezra Koenig's a likeable enough frontman. Rostam Batmanglij makes mercury patterns in the air with his afrobeat-inspired guitar lines, and the better moments from Vampire Weekend and Contra are sufficiently engaging to make you forget any concerns that the whole thing is a student prank. But in a week when I've experienced genuine youthful hysteria in all its fearsome force, Vampire Weekend cannot help but seem insincere and arch.

Next Week:

Simon Price encounters two generations of loopy American blondes with Hole's comeback and Lady Gaga's The Monster's Ball tour