Florence and the Machine: Symphony of Lungs review – one crescendo of ecstasy after another

Will it surprise you to learn that Florence Welch’s orchestra features not one, but two harps? That there is a lute and a rainstick, and a violin solo so furious that it feels like a devil is being conjured? As the grand high witch of maximalism, the Proms is the ideal way for Welch to revisit the pained howl of Lungs, her 2009 debut album that wears its heartbreak like a scar. “When I first heard Jules’s orchestration, I cried,” she tells the audience in her whisper-soft speaking voice. “This album is about feeling and I never thought anyone could add more feeling. But Jules did.”

She walks out in a red Rodarte gown that is 90% sleeve, evoking the bruised and bloody heart of 15 years ago. Each of Jules Buckley’s orchestral reworkings teases something new from the occasionally patchy collection of songs. Girl With One Eye becomes a campy musical theatre number as Welch vamps around the stage and the bassoon channels You’re a Mean One Mr Grinch; the fluttering woodland flutes heighten the emotional warfare of My Boy Builds Coffins; the tidal wave of feeling crashing around during Rabbit Heart ratchets the crowd to their feet.

And anchoring it all is that voice, wide-mouthed and guttural but not gravelly, dredging up long-buried emotions and recasting them with tenderness and a kind of joy. Welch claims that her range has shrunk in the intervening years but you can rarely tell; the huge notes hit like a cannon firing, her head voice peaking with all the softness of a flurry of snow.

“Everything’s a big crescendo,” she said of her songwriting in 2011 – and so it is here, heightened by the power of tens of musicians. The breaking waves engulf the audience every time: by the time we reach Dog Days Are Over (with an operatic verse chucked in, because why not), the atmosphere hits a kind of ecstasy that you rarely get to feel without chemical intervention. Spirits are channelled and danced with, as Buckley and Welch give an unforgettable performance.

• Available to listen again on BBC Sounds until 14 October. The BBC Proms continue until 14 September.