When Bryn Terfel appears as Scarpia in Tosca later this week, it will be his first performance as the evil Chief of Police in Puccini’s opera since the Royal Opera’s production opened over three years ago. There have been a couple of revivals in the intervening time, but with other artists, and the Welsh bass-baritone has been resting the role, in order to come back at it fresh.

He tells me over lunch in the ROH canteen that he likes to work that way. “I felt I needed a break from the part,” he says, “It’s good to perform it and then come back to it some time later, especially with these big roles. I’m very comfortable with it now and I think Angela Gheorghiu is too. She’s done the same thing.”

“You can throw yourself too wholeheartedly into a role like this,” he adds, “he’s not nice to play and you go out of your comfort zone. Maybe, now, my Scarpia’s a bit more thoughtful.” I ask him if he has to find a way into a role that is so unsympathetic, to seek a justification for the character’s behaviour. “No, you just relish the evil,” he grins.

I ask him how he feels about Jonathan Kent’s production, which, when it was new, some felt didn’t get significantly away from the traditional feel of the 40 year old Zefferelli one that preceded it. “Things move on,” he says, “but I think the Royal Opera House maybe played safe a bit. If you’d wanted a completely different style of production, you’d have gone for another director. I think what Jonathan has done is bring it to a much more intense level. It’s intimate and every movement has a reason.”

Angela Gheorghiu

He feels that the production (now revived by Stephen Barlow) has grown along with the performances of its two leads, both reprising their roles this time (Gheorghiu has stepped in just recently for an indisposed Deborah Voigt). “Angela remembers everything. She’s a bit like a computer,” he says. It brings us on to the potentially thorny question of the Romanian soprano’s reputation as a difficult artist.

“Somebody’s going to be unhappy at some point; it can’t all be roses,” he says. I question whether the fit between a colleague who’s seen as a diva and one who’s renowned for his good humour and easygoing personality is a good one. “I take her as she is,” he says breezily, “there are elements of insecurity (I’ve seen her shaking on the stage like a leaf). But I’ll tell you, there was one rehearsal where she sang “Vissi d’arte” and it really got me. It’s a memory I’ll take to my grave. I sent her a text and said ‘you totally got me’. Enough said.”

It reminds of something Jon Vickers said of Maria Callas, that he didn’t care what she was like offstage; all that mattered was the result. “Ah, that’s good,” says Terfel, “we could say the same thing about Angela. When you have a voice like that, it doesn’t matter; it’s pure nectar.”

Die Meistersinger

Terfel has one of the biggest challenges of his career coming up in 2010 – playing Hans Sachs in Die Meistersinger in Cardiff for Welsh National Opera. “It’s huge,” he says, “but I’m looking forward to it. Just got to learn it now.” It follows on from his debut as Wotan at the Royal Opera House four years ago, itself an enormous landmark in the singer’s career.

He famously dropped out of the full cycles of The Ring 18 months ago, due to family problems, and London didn’t get to see his Wanderer in Siegfried. He will play Wotan/Wanderer in the complete Ring, in a brand new production at New York’s Met next year and will then return to Covent Garden for further cycles in 2012.

He felt that Keith Warner’s production, which received a rocky reception on its first outings but seemed to grow in popularity by the time it completed its cycles, was marred by cluttered sets. “I felt sorry for Keith,” he says, “because he lost his designer. It never quite came together.” Sets in Wagner productions are something he warms too, as we talk about his recent house debut at the ROH as Der fliegende Höllander. “I went into that saying I wanted a boat and no rake and we ended up with a rake and no boat. My back doesn’t like rakes and it’s time designers got to understand that steep stages might look good but are not always good for singers.”

Sweeney Todd

From Wagner we move on to talking about Sondheim’s Sweeney Todd, a part he played in a semi-staged concert at the South Bank a couple of years ago. “It’s very intense,” he says, “I can’t imagine how Len Cariou (the Broadway original Sweeney) managed eight shows a week.” He says any rumours (some have gone the rounds) about him touring it with Maria Friedman are not true, although he adds “I’d love to do it again; I’d jump off a cliff to do it.” He enthuses about the opportunity it gave him to work with a living composer, the only time he’s done so.

Present and future

The next few years are all accounted for, with Hans Sachs and Wotan his main focus. There are no roles he covets, even glancing well into the future. He’s pretty relaxed about the jobs in hand and seems very content in the present moment.

Terfel is all amiability and warmth, as friendly a companion as you can expect from a world-class opera star. We end by strolling to the tube and he continues chatting, taking time to say hello to a passing policeman along the way. “A Welshman,” he observes. He warms to his fellow countrymen and notes my surname, pleased to hear that my roots are in the Rhondda Valley.

He’s also amused that we share the same birthday. “We Scorpios!” he laughs. I can’t say I’ve ever been made to feel like pals with an interviewee before but I get the feeling the next time we meet, we’ll pick up where we left off. Bryn Terfel is a great artist with a common touch. He somehow has a way of balancing high art and populism which no other singer has achieved. That Meistersinger is going to be worth travelling to Cardiff for.

Tosca opens at the Royal Opera House on Thursday 9 July and plays for five performances through to 18 July. Tickets are available on 020 7240 1200 or at www.roh.org.uk

- Simon Thomas