Florence + The Machine, Shepherd's Bush Empire, London

Bewitched by a true siren

Few people can pull off the tousled hair and billowing-caped flower-power look these days. Florence Welch of Florence + the Machine, however, looks at home being all twitchy fingers and spiralling wrists, resplendent in some sort of diaphanous chiton. She is majestic, like John William Waterhouse's Circe, with the awestruck audience as her swine.

Her swine and her swains, that is, judging by the many shouted declarations of devotion that the singer received. And well she might, with a charisma and stage-presence rarely seen among the bouffanted popstrels or pierced mock-hellians that make up the ranks of modern-day frontwomen. Florence is like something from another time, when icons came from myths or altars, not TV talent contests.

In fact, this flame-haired Boudicca was discovered in a toilet, and she sang a cappella the song that won over her now-manager in the stalls. Hardly the most exciting of her set list, Etta James's "Something's Got a Hold on Me" nevertheless showcased Florence's epic range and perfect pitch to great effect. An acoustic segment proved similarly complementary – so much goes on in any given Florence + the Machine track (there are five of them, plus a string quartet, after all) that it is often hard to pay due attention to Florence's swooping and soaring vocals. But she sang "Hurricane Drunk", one of the real anthemic, rollicking power-numbers from her Mercury-nominated album, Lungs, accompanied only by a harp and a guitar. Starting alone, she managed to be consistently perfect when the instruments joined in. Her control and instinctual grasp of any given melody is as impressive as her performance style, which is a mesmerising mix of the slick and modern, and the goosebump-inducing arcane.

Florence's stage is bedecked with flower garlands and bracketed by two ornamental birdcages; she is like some greenwood deity, riding those volleys of thudding drums. Yet where a band of this size and volume, fronted by a singer with such an enviable set of pipes, could easily descend into a cacophonous mêlée of diverse rhythms and harmonies, Welch's Machine is a well-oiled one, and its constituent parts were neither drowned out nor deafening, crashing through high-octane numbers like "Howl" and "Drumming Song" with accomplished melodrama.

With a concert persona such as this, it is comforting – if slightly disappointing – to hear Florence so human, not to mention humble, as she chats between songs; she is girlish and, some might say, calculatedly overwhelmed by the attention she receives. There have been several comparisons already with Kate Bush, and Welch is certainly as weird, witchy and wistful as that other Babooshka, but she has an energy and vitality that other stage sirens in the indie category often lack. Welch – with her copious talent and gift for enthralling – is without doubt a star who is here to stay.