Edward Sharpe and the Magnetic Zeros, Old Vic Tunnels, London

The Old Vic Tunnels are spooky relics of 19th-century engineering that lie hidden beneath Waterloo Station and reek of Jack the Ripper. Edward Sharpe and the Magnetic Zeros are West Coast troubadours with a messianic frontman whose power pop comes straight out of the late 1960s. Put venue and band together and what you get is one deliriously surreal night out.

ES&TMZ burst on to the scene in 2009 and their elevation to cult status was virtually instantaneous. They seemed to have emerged from a time capsule – the missing link between The Mamas and the Papas and Hair. Every period detail was perfectly preserved, and their debut album – Up from Below – carried so much life-force that to get into it felt like exposing yourself to danger.

Much of that was to do with the band's leader, Alex Ebert, who is not the first musician to realise that you can do a great deal more with an alter ego than you can as yourself. Perhaps he should have called the band Shaman Corner; instead, he came up with the concept of Edward Sharpe – and the message from the bearded, wild-haired, be-robed, lost-in-the-desert figure who flailed round the stage and then got down off it and walked among the crowd was unmistakeable.

Quite how seriously we were meant to take Ebert was open to question. Could he have turned out the way he was without Billy Graham, Charles Manson or indeed Russell Brand coming before him? He conveyed as much jokiness as devilment, and his resemblance to John Cleese's Wise Man character in Life of Brian was somewhat undermining of his apparent attempts to lead his audience to higher planes of existence.

This was much more than a concert. Taking over the venue for five nights, ES&TMZ offered circus-entertainment preliminaries that included fire-eaters and acrobats, and which sharpened the sense of anticipation around the appearance of the band itself. That was not due until 10 o'clock, and in the end – after Ebert had tested the audience's patience by arriving on stage only to introduce a mind-reading act – the music didn't start until 10.40.

Any goodwill Ebert had squandered he quickly retrieved as he set up the spare percussive rhythm that presaged the flowering of "40-Day Dream", a song, like so many of ES&TMZ's, whose appeal is essentially child-like. The extent of ES&TMZ's reach into the pool marked "timeless classic" is remarkable – big, simple, swaying choruses suffused with the spirit of abandon and which continued through the skipping beats of "Janglin" , the more contemplative "Up from Below", the evangelical "Carries On", and the hectic hoe-down that was "Home".

With a gaggle of around 10 musicians on stage – it was hard to count them through the dry ice – and their mix of the exultant and the eccentric, ES&TMZ have drawn comparisons with Arcade Fire, and who knows one day they too might sell out the O2. It would be great to see them there – they've got the sound to fill it – but it's very doubtful if, as here, they'd be allowed to end with dozens of audience members up on stage, Ebert complicit in the anarchy until his microphone packed up and anxious-looking stage hands were left to restore order.

Ends Sunday (0844 871 7628)