Sweeney Todd (London Coliseum)

They toy with the idea of a concert performance then subvert it before our eyes. It turns out that this much-heralded import by English National Opera from the New York Philharmonic, which has enormous fun being naughty with stuffed-shirt opera house conventions, outstrips the long-running Chicago and even John Doyle's actor-musician Sweeney Todd as a staged concept.

Director Lonny Price wrings every ounce of humour from Stephen Sondheim's masterwork, with sight gags galore and a wonderful comic turn from Emma Thompson. If only the composer hadn't dubbed Sweeney Todd 'a musical thriller' – in the American sense of horror (cf. Michael Jackson) – because chills are absent. Victims aren't cut, bodies don't spasm when stung by the blade; and when, in the reprise of "Johanna" the dead calmly exit upstage, that blissful dislocation of Todd's thoughts from his deeds goes for nothing.

I can only imagine the howls if its omissions were reversed. ('Horror but no comedy? Typical ENO.') The focus is diffuse and all suspense defused as Price shows more interest in playing post-modern games than in rendering the drama. By the time we reach his pièce de résistance – a bum note of a trombone trick – the bloodied remains of Hugh Wheeler's book lie slain.

'The great bass-baritone is a bear of a Sweeney'

And yet, and yet… there's a hand-picked 30-strong ensemble that could rustle up a few good cover casts between them, while under David Charles Abell's baton the ENO Orchestra, which is the only in-house element of the show, plays the hell out of orchestrations by Jonathan Tunick that can rip the heart full-on or slice the skin with a touch of a chime tree.

As for the principals, you'll blink to believe the list. Philip Quast, no less, plays the evil Judge Turpin with silken depravity, and Alex Gaumond is pure Dickens as his sidekick, Beadle Bamford, in a performance that will make you regret the abridgement of his "Parlour Songs". John Owen-Jones is unlikely casting as Pirelli, the quack barber, but he easily steals his moment.

Sweeney Todd's juvenile leads are rarely as well matched as Matthew Seadon-Young and Katie Hall are here, and Jack North's Hobbit-like Tobias has exactly the right blend of guilelessness and warmth.

The divine Ms Thompson, with her brilliant timing and comic asides, offers unbridled joy as Mrs Lovett. She sings the hell out of the score, too, which will come as no surprise to anyone who saw her in Me and My Girl. Decked out as a scarlet Mrs Overall, she oversteps boundaries with glee and at one point even stole a stole from a press-night worthy. Thank goodness she overdid the head notes in her opening number, otherwise I'd have suspected superhuman powers at work.

Paired with this force of nature, what chance does Bryn Terfel have? Plenty, thankfully. The great bass-baritone is a bear of a Sweeney and he gives a superbly bold performance. The eyes gleam and flash, the voice roars before dropping through mezza-voce to near-inaudibility. The only thing missing from his armoury is litheness, a quality that would have been welcome as he prowled the stage in "Epiphany"; but my, the man can sing Sondheim. By the time he dropped his blade I was in bits.

Sweeney Todd is at the London Coliseum until 12 April