There's an elephant in the room, so let's get it out of the way. Four out of five of the reformed Steps, back after an 11-year hiatus with a record-breaking tour and a hit reality show on Sky, look pretty much the same as they did when they left off. One of them does not.
Claire Richards has yo-yoed in dress size since Steps split. It's immediately obvious that the management hasn't packed her off to the gym, and that's something to be applauded. There are a few "fatty" heckles, but they're outnumbered by loud cheers which are, I hope, genuinely appreciative of seeing someone in a pop group who exists outside the narrow range of approved body shapes.
I never warmed to either of the Steps blondes first time around. Lisa Scott-Lee, the St Asaph brunette, was always the obvious fox of the group. But tonight it's Claire, now at what she calls her "happy weight" and looking like someone who loves life, who is arguably their sexiest member.
This reunion was always going to happen. Pop has a vacuum for a girl-boy band at the moment, and Steps haven't burned as brightly apart as they did together, to put it mildly.
The five emerge from Perspex pods, as though cryogenically preserved since 2001, and begin dancing with the deliberately stiff movements of sci-fi action toys. It's a bog-standard pop show, with lots of chiffon, satin and sequins in garish primary colours, a bit of fire-juggling, the obligatory bare-chested beefcakes and confetti cannons, and a split-the-audience dance competition for "Last Thing on My Mind", "Better Best Forgotten" and "Love's Got a Hold on My Heart" which turns the Echo Arena into a mass aerobics lesson, like a Scouse re-enactment of that North Korean video clip.
Being the opening night, there are glitches. A small rectangle of the screen remains defiantly black throughout. During "5, 6, 7, 8" the backing tape goes out of synch, and does it again for "One Night Only", leaving Faye, sprawled on a giant shoe, looking dafter than she already might.
There's a solo section, led by Lee Latchford-Evans, Steps' boring token hetero male, encompassing pop covers (a Kylie/Gaga medley and a Maroon 5/Rihanna one) and rock anthems (Journey's "Don't Stop Believin'", Bryan Adams's "Heaven"), and it ain't over till Claire Richards sings. Rising up in an enormous fishtail dress, she belts out a big ballad, giving it the full "I can really sing" treatment.
Steps remain as functional as you'd expect a creation of the wilfully anti-art Pete Waterman to be, and, of course, highly derivative. "One for Sorrow" borrows heavily from Abba's "Winner Takes It All", "Deeper Shade of Blue" from Robin S's "Show Me Love", "Stomp" from Chic's "Everybody Dance"... and that's before you get to actual covers such as their shockingly lumpen "Dancing Queen".
Alex James be damned: Steps are pop's most prominent cheesemongers. But Noël Coward's claims for "the potency of cheap music" remain true. As the show reaches its inevitable coat hanger-armed "Tragedy" finale, a funny thing happens when I get up to leave. My face hurts, and my leg aches. I've been smiling. And I've been tapping my foot.
"This is the Metropolitan Police," says the old provocateur. "The people are revolting. Go home." But we've only just arrived.
There's a body of opinion which holds that Public Image Ltd were never the same after the departure of Jah Wobble and Keith Levene: in a recent book, post-punk chronicler Simon Reynolds described PiL's later efforts as "brand-disgracing". There's also distaste, in the same quarters, at the idea that John Lydon is carrying on as though he is PiL.
I've always found this strange: no one gives Mark E Smith a hard time for carrying on as though he is The Fall, and the first two PiL records I ever heard were "The Flowers of Romance" (post-Wobble) and "This Is Not a Love Song" (post-Wobble and post-Levene). Both blew my teenage mind. The latter is oddly mournful tonight, but "The Flowers of Romance" is utterly spellbinding.
Lydon has explained his much-derided butter ads have helped to fund the forthcoming PiL album, and on the evidence of some of tonight's extracts, it's money well spent. Deranged shout-a-thon "Lollipop Opera" stands out. "You may not know the words," he says, "but in a year's time that one'll be a lot of PiL fun."
He may look oddly academic now, that asymmetric ginger crop offset by professorial spectacles and a lectern, but sometimes you catch that famous piercing stare (a result of a squint brought on by a childhood bout of meningitis) and find yourself in the middle of a Pistols flashback: there he is, Johnny Rotten in that Vivienne Westwood muslin asylum shirt.
Then you're shaken out of it by the realisation that punk nostalgia is the last thing PiL are about. As if to eradicate any doubt, tonight we hear early classic "Albatross" ("Sowing the seeds of discontent/Getting rid of the albatross") which can be read as a barbed farewell to the retrogressive straitjacket of the punk scene.
As Wobble himself puts it, "reggae was always the engine room" of PiL, and it's all about the bass, played these days by Scott Firth. In some songs more so than others.
Swigging from a bottle of Martell ("it's medicinal"), Lydon wails his way through "Religion", that excoriating rebuke to the abusive priests of his youth, and demands more and more bass until your ears feel ready to bleed and your teeth to fall out.
"Be not afraid of no man's religion," he declaims as it ends. That's Lydon for you: double negative.
Bloody-nosed gonzo rocker turned motivational speaker Andrew WK parties hard at The Forum, London (Thu); the Academy, Manchester (Fri) and The Garage, Glasgow (Sat). Meanwhile, lush-lipped, big-haired, vintage-styled songbird and controversy magnet Lana Del Rey plays a stripped-down set at London's Jazz Café (Tue).