Denys Baptiste on stage at the Queen Elizabeth Hall

An 80-voice choir and a string quartet served notice of the ambitions of saxophonist Denys Baptiste’s reworked celebration of Martin Luther King’s “I Have a Dream” speech. Baptiste first staged Let Freedom Ring 10 years ago, using a collage of Ben Okri’s poetry, graphic documentary film and muscular jazz to capture the call-to-action sentiments of the second half of King’s speech.

This concert, marking the speech’s 50th anniversary as part of the Southbank’s The Rest Is Noise festival, opened with a new work, Now Is The Time, based on its context-setting first half. The 13-piece band was just as muscular, but now the graphics were scratchy, slightly abstract and featured footage of Lemn Sissay reading his poems. Periodically the choir, largely unaccompanied, would sing an anthem of the time – “We Shall Overcome” sombrely; “We Shall not be Moved” at a fair old lick. They captured the sense of a movement on the march, but still seemed more add-on than essential feature.

The first half was tentative in places – poetry and music didn’t sit, and occasionally you could see the join – but the second was a confident: rousing protest against injustices present and past. Okri’s pre-recorded poetry was far-reaching and optimistic, and the movement from film to stand-alone music was seamless.

And the music, in both pieces, certainly stands alone. It bursts out at angles and, structured on the rhythmic patterns of King’s oratory, twists into awkward changes of tempo. Best of all, it is as engaging as Baptiste’s warm-hearted tenor sax. The string quartet bustled and shimmered, the brass riffed in response, there was a New Orleans march, and gospel and soul were in the mix.

Periodically, a soloist would make a mark of their own, inspired by images of water canons, burning crosses and a sign reading “White at the front, coloured at the back” being unscrewed from inside a bus. The upward glide of Omar Puente’s violin and Nathaniel Cross’s soul-searching trombone stood out. The piece ended with more contemporary footage of protests from across the world being met with the same violent response, and the choir urging us to sing “Free at Last” as a dream yet to be fulfilled.

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