It's always the quiet ones you have to watch – the peripheral faces in the penumbra, at the edge of the spotlight's glare. So it was with punk rock, when a handful of minor Sex Pistols hangers-on later became the players who would show a torchlit route out of the bowdlerised, codified cabaret that punk had become by the late Seventies. Adam Ant, Steve Strange and, above all others, Siouxsie Sioux.
Few would have predicted it in September 1976, when the teenage Susan Ballion led a scratch Siouxsie and the Banshees at the 100 Club's Punk Special, wearing a swastika armband she'd spend a lifetime answering for, caterwauling through a 14-minute rendition of The Lord's Prayer, and prompting a backhanded compliment from the Pistols' Glen Matlock: "I don't know what it is, but it's not rock'n'roll."
The Scream (1978) and Join Hands (1979) pioneered a kind of cryogenic psychedelia, their combination of icy, abrasive harshness with lyrical mystique and previously verboten artiness laying the blueprint for what would later be known as Gothic rock. The 1980 album Kaleidoscope, though, is what Sioux chooses to perform in full when ending a half- decade absence for Yoko Ono's Meltdown.
With its themes of mental trauma and voyeurism – and, let's be blunt, cracking tunes (you'll know "Happy House" and "Christine") – that album defined the Banshees sound. And if the word "icon" is overused, make no mistake: on stage and in the flesh Siouxsie is the living, high-kicking, wrist-twirling, real thing.
At the Royal Festival Hall she's looking incredible: the unmistakeable raven hair, death-mask eyes and scarlet scowl augmented by a white PVC outfit that's part kabuki, part Action Man parachutist, part Clockwork Orange droog.
A sweat-drenched midsummer hour later, Sioux vows: "Next time I come back after five years, I won't wear vinyl."
She's sounding ferocious too, the voice – always an obstinate semitone below the natural melody – as impressive as her ability to get her foot vertically above her own head. And her band, a lean three-piece, manfully make up for the absence of actual Banshees.
Kaleidoscope is followed by a second half that includes "Dear Prudence" (watched by Ono, the widow of the man who wrote it), blues standard "Careless Love" astride a high-backed chair, and the ultimate horror-punk anthem, "Spellbound".
The incongruous party balloons thrown by misguided fans, along with the Venetian blind backdrop, are an inadvertent throwback to old Top of the Pops appearances when the Banshees were gloriously out of place. Sioux is never truly in her element unless she's kicking against the pricks.
Accidentally chiming with the times is always pleasing, but in the hands of Pet Shop Boys (O2, London *****) it starts to look deliberate. "Integral", written in 2007 as a response to the Blair government's identity card scheme, suddenly feels even more relevant: "If you've done nothing wrong, you've got nothing to fear/If you've something to hide, you shouldn't even be here/Long live us, the Persuaded 'We'..."
It's one of the many ways PSB, a band who have been around long enough for Chris Lowe's "Boy" cap to be fashionable three times over, sound shiny and new on their current tour.
Lowe's mixology skills are to the fore – the segue from "I Wouldn't Normally Do This Kind of Thing" into "Suburbia" is a thing of beauty – and the trick of repurposing a macho rock cover, in this case Springsteen's "Last to Die", and running it into more standard camp fare like Bernstein's "Somewhere", echoes their chart-topping "Where the Streets Have No Name/Can't Take my Eyes off You" medley.
As always, it's a costume spectacular of deadpan Dadaism – ballet dancers in buffalo headdresses, mirrorball helmets, and the laser display they break out for "I'm Not Scared", throwing vortices of green beams around the concrete cavern of the O2, are among the best I've ever seen.
The material from the forthcoming Electric holds up well, notably "Thursday", but we're soon into a run of "Rent", "It's a Sin", "Domino Dancing", "Always on My Mind", the hits from PSB's imperial phase – Neil Tennant's own wonderful term; he always did have a way with words.
The planned serendipity continues to the very end, when "Go West", a cover that alludes to the false dreams raised by the fall of Soviet communism, is followed by "West End Girls", which alludes to the revolution that started it all. It's almost as if they know what they're doing.
Tom Tom Club, the punk-funk pioneers led by Talking Heads rhythm section Tina Weymouth and Chris Frantz, play the 100 Club, London (Mon); Thekla, Bristol (Tue); Brudenell Social Club, Leeds (Thu) ahead of weekend spots at Glastonbury and the Eden Project. Meanwhile, original Jersey Boy Frankie Valli brings The Four Seasons to the LG Arena, Birmingham (tomorrow/Sunday) and Royal Albert Hall, London (Tue & Wed).