Sir John Eliot Gardiner's new recording of Mendelssohn's Reformation Symphony with the London Symphony Orchestra is absolutely startling.

It shouldn't be, because it is a very familiar work that has received myriad treatments, in concert and on disc. But Gardiner, with consummate thoroughness, has taken a completely fresh and forensic look at the music, and, without doing anything radical, has virtually reinvented the symphony. It blazes anew: it's as simple and complex, as direct and sophisticated, as that. There's not a breath, a phrase, a dynamic or a strand in the texture that has not been scrutinised and grilled as to its function, purpose and place in the music. And the whole damn thing bursts into flaming life. I know this symphony; or I thought I did. The LSO, here, is the best period band in the world, while the two overtures, Ruy Blas and Calm Sea And Prosperous Voyage, are masterpieces still in waiting.

Michael Tumelty