OWAIN Arthur bounces on to the stage of One Man, Two Guvnors, buttons straining on his loudly checked three-piece suit.
With his rotund physique and a chortle so fruity it's virtually chutney, he's every inch the hapless Francis Henshall, a down-at-heel musician in desperate need of a good feed. Hunger drives him to run errands for two shady crims newly arrived in town; neither knows he's working for the other. Chaos ensues.
It's the show's last London matinee before the tour out here and while the rest of the cast stick to the rapier wit of the script, Arthur's appearance on stage signals a lot of high-octane tomfoolery that seems totally fresh.
So, I ask him afterwards, how much is spur of the moment?
It's a mix of improvisation and structure, he says, laughing (he laughs a lot). ''It's the type of show where things can go wrong and you can acknowledge it, because there's no fourth wall.'' Translated, this means audience members are both hauled up on stage and appealed to on a regular basis.
It's all in the spirit of what Arthur calls the ''holy grail'' of comedy, commedia dell'arte, and One Man, Two Guvnors, Richard Bean's update of Carlo Goldoni's 18th century Servant of Two Masters, is set in the petty-criminal world of 1960s Brighton. Think Brylcreem, beehive hairdos and Carry On-style innuendo.
Originally understudy to James Corden, for whom the show was commissioned by London's National Theatre, Arthur watched the Gavin and Stacey star woo audiences and critics. He'd heard that the play's director Nicholas Hytner was looking for a high-profile actor to replace Corden when the original cast transferred to New York last April, but never expected to get the part; understudies are always the bridesmaids, never the brides.
He'd taken the role because, he reckoned, it was worth it for the four performances standing in for Corden when he had other commitments. It was on the first of these, with an audience full of casting agents and critics, that Hytner tapped Arthur on the shoulder at interval and told him that the part was his.
He laughs again at the memory.
''It was a do-or-die evening, I can't think of ever being under more pressure; I had nothing to lose and everything to lose. So many things could have gone wrong, but I was lucky.''
He's being modest. Several critics have said that Arthur is actually as good if not better than Corden [who won a Tony on Broadway], an assessment Bean agrees with.
''With Corden as Francis Henshall, you get a lot of James' personality, as in 'this is James Corden doing the part','' he says. ''But with Owain you get less of that, partly because we don't know who Owain Arthur is, but also because I think he is Francis Henshall.''
Arthur, 29, isn't a complete unknown of course; he's worked with the Royal Shakespeare Company and played in Alan Bennett's The History Boys at the National Theatre. But this is his biggest role to date.
He's quite delighted to be coming our way, he says in his strong Welsh lilt, with the tour anchoring him in Australia for the best part of four months.
I expect him to say he'll be hotfooting it back to a juicy role in the West End but no, he'll be catching up with friends while in Australia.
And then, he says, he wouldn't mind auditioning for some parts over here.
''I've heard there's lots of quality theatre.
'I've lots of friends who've worked there for a year or so and have heard only good reports,'' he says. He's keen on film or television work too, if anyone's interested.
''What sort of roles?'' I ask. Something a bit different from his present character, he answers, with his big-bellied, knowing laugh; ''something with more weight''.
One Man, Two Guvnors is at the Adelaide Festival February 28-March 9; Sydney March 30-May 11; Melbourne May 17-June 22.