Bryn Terfel: Bad Boys, Royal Festival Hall, London

Bryn Terfel arrived in the capital armed with countless sneers and as many ways to make mischief. His latest album, Bad Boys – a comprehensive gallery of operatic rogues and villains – was now a tour, and there was a big, glossy, souvenir programme to prove it.

But at least this latest participant in the South Bank's International Voices series offered value for money – the big Welshman doesn't short-change us, not even when he's in the guise of that prize quack Dr. Dulcamara whose lotions and potions are cheap for a reason.

It was as Dulcamara (he of Donizetti's L'elisir d'amore) that Terfel – his features already fixed in a suitable expression of contempt – arrived on stage to join his touring band, Sinfonia Cymru, a lively youth orchestra culled from outstanding student talent who, under conductor Gareth Jones, provided the evening's accompaniments and between-number "groutings", like the Ballet Music from Gounod's Faust and Saint-Saens' Danse Macabre (with a mean violin solo from Cerys Jones).

The odd prop or costume accessory distinguished between the evening's incorrigible baddies, but it was the engaging Terfel, as himself, who made the introductions. That's the thing about this man: he's a big international star with the common touch; a peoples' person. And even as you're thinking, "isn't this a bit down-market, a bit cheesy?" you are charmed. How many opera stars do you know who could have you singing "Happy Birthday" (to him) minutes after the start of the show?

But then when you are as good as Terfel you can get away with just about anything. You can lead your conductor into the Wolves' Glen on the end of a 12-bore shotgun and immediately undercut the tomfoolery with a storming account of the evil huntsman Caspar's aria "Schweig, Schweig". You can sing "Mack the Knife" in German with an improvised street band (Kurt Weill's original orchestration albeit with a synthesised accordian) and still make every word explicitly understood; and you can sing Gilbert and Sullivan – "When the Night Wind Howls" from Ruddigore – with a clipped English accent to have your countrymen squirming.

I wish Terfel had given us "Epiphany" from Sondheim's Sweeney Todd (as on the album) instead of just "The Ballad... " (and that with a rather pallid chorus – London Welsh Chorale, Canzonetta and The Consort of Voices – instead of well-defined individuals), but his whistling Mefistofele (attention all canines) had him delving so deep into his bass extension as to almost, but not quite, slip from song into growl; and Iago's "Credo" from Verdi's Otello made something so toxic of the final word "nulla" ("nothing") as to eradicate once and for all any notion of the hereafter.

Inevitably, Baron Scarpia brought down the proverbial curtain on act one just as he does in Puccini's Tosca. Terfel has sung the corrupt Chief of Police many times on stage and even without the benefit of context his lust for opera's most celebrated diva is as palpable as it is distasteful. It was a stroke of genius on Puccini's part to counterpoint Scarpia's carnal desires with a full-blown Te Deum, but I doubt even he reckoned on a rolling bass-baritone that could so seductively ride the choral ensemble as Terfel did here. I say bass-baritone, but Terfel even poached a tenor number – "It Ain't Necessarily So" from Porgy and Bess – and so well characterised was his whining drug-pusher Sportin' Life that you almost bought the vocal deception.

He's an artist, this man, but more than that he's a born showman. And when he's bad...

Touring Birmingham Symphony Hall (18 Nov); The Bridgewater Hall, Manchester (22 Nov); City Hall, Newcastle (25 Nov) (www.raymondgubbay.co.uk)