What does a rock band do when it reaches middle age? It’s a puzzle Manic Street Preachers have been wrestling with as the group that boasted they would sell 16 million copies of their debut album and then split up, against all odds, have been together for more than 30 years.

Twenty years on from their Brit Award winning, multimillion selling late-Nineties commercial heyday, this most self-aware of groups have questioned their own relevance as they reach 50. Formerly so surefooted, they now seem to be fumbling for an answer. The promotional campaign for new album Resistance Is Futile, their 13th, has not gone smoothly: a promo shot of the band looking uncomfortable wearing creased suits was cruelly mocked online, while recent interviews have seen the usually bullish bassist Nicky Wire come across as a surprisingly centrist dad, bemoaning modern life with some weary it-was-better-in-our-day rhetoric.

Resistance Is Futile – full of Manics’ usual working class intellectualism with references to Yves Klein, Dylan and Caitlin Thomas and Francis Bacon – does enough to justify their continued existence with some fine orchestral indie rock. But tonight’s nearly sold out show at Wembley Arena is where the Manics prove the fire still burns inside. Tonight starts as only a Manics gig can: a quote from Phil Ochs glares in ominous red on the big screen: “In such ugly times the only true protest is beauty”. It then roars into action with an epic opening that links Manics’ past and present. Resistance Is Futile’s lead single “International Blue” is classic, swaggering, radio smash Manics, an updated, streamlined take on their hymn to existentialism “Motorcycle Emptiness”, which, sang second here, sounds majestic as ever.

Songs from their all-conquering period retain their defiance – the sweeping “Everything Must Go”, a fierce “Masses Against the Classes” (a Camus quoting number one single, lest we forget) – but new songs are played with just as much gusto. Best of those is singer James Dean Bradfield and guest Catherine Anne Davies (aka The Anchoress) doing their best Elton John and Kiki Dee, constant eye contact and all, on “Dylan and Caitlin” – the most melodically satisfying the Manics have been for some time. It was one of three duets with Davies, whose star turn on alt-ballad “Little Baby Nothing” was one of the night’s highlights.

This being the Manics, there are moments of obstinacy. There’s an acoustic version of their most ferocious track “Faster”; there are odd rarities in the shape of “4 Ever Delayed” and “Horses under Starlight” as well as a dumb but ultimately fun cover of Sex Pistols’ “No Feelings” sung by Wire, who by now has changed into leopard skin skirt and white fedora. “If you’ve got the finest pair of legs in rock ‘n’ roll, you might as well use them,” he says.