Like the flesh on Sweeney's victims, it's been flayed. We're down to the bare bones of the harmony - and it's scary. Not much consonance now. Even the sweetest ditty, be it a derivative of some Victorian parlour song or a lusher romantic ballad (like the wondrously elusive 'Johanna'),is remorselessly curdled by the displaced harmonies - only now there's no protective Broadway gloss.
A nine-piece band is the palm court ensemble of one's nightmares, string trio violated by a quartet of subversive winds. It's grubby, and music-hall gaudy where it needs to be. And the voices (praise be) are unmiked. The thinning-down of the choral writing again lays bare the bizarre chordings and Sondheim's marvellous use of eerie falsetto and sopranos in altissimo, like factory whistles.
One may miss the orchestral weight, the driving string ostinatos of the opening ballad, the crunching brass pedal notes of Sweeney's 'Epiphany' - and Alun Armstrong (like one or two of the principals) is an actor first, a singer almost incidentally. But what a powerful, believable presence and how he soars tremulously in the 'aria' to the memory of his Lucy. He and Julia McKenzie, sporting her most raucous Marie Lloyd belt voice as the lovably ghastly Mrs Lovett, are a turn-and-a- half in their Act 1 finale 'A Little Priest' - a slice of comic music-hall genius from Sondheim that is a very long way from the heartbreaking understatement of Tobias' 'Not While I'm Around', still one of his best and most discreet songs.
'Sweeney Todd' is in rep at the Cottesloe, National Theatre, London SE1 (Box office 071-928 2252)