Bryn Terfel interview: Britain's best-loved baritone looks back on his 'wonderful journey' through the world's greatest operas

Bryn Terfel takes the lead in Wagner's 'Der Fliegende Holländer', which opens tomorrow night at the Royal Opera House, and follows that by starring with Emma Thompson in 'Sweeney Todd'. She can floor you with a sentence, he tells Jessica Duchen

Bryn Terfel in ‘Der Fliegende Holländer’ (Clive Barda)

Gods. Murderers. Dictators. Ghosts. Bryn Terfel is used to playing them all, and more. The towering bass-baritone from north Wales, who turns 50 this year, is probably the best-loved figure in British opera today: gigantic in stature and personality, with a booming voice that is effortlessly flexible and expressive even when speaking, never mind singing. So huge a presence is he that it is almost startling to find him arriving for a rehearsal of Wagner's Der Fliegende Holländer (The Flying Dutchman) at the Royal Opera House on as modest a contraption as a bicycle.

The immediacy that Terfel brings to the stage is, though, far from a matter of sheer heft. Vivid colour and detail are even more central; it is as if he puts his characters under a magnifying glass. As those characters can include such larger-than-life individuals as Verdi's Falstaff, Puccini's villainous Scarpia in Tosca, Wagner's Dutchman, Wotan in the Ring cycle, or Hans Sachs in Die Meistersinger von Nürnberg, plus Stephen Sondheim's Sweeney Todd, the picture that reaches the audience is substantial to say the least.

Much expectation hangs on Terfel's shoulders right now: next month he sings Sweeney Todd, with Emma Thompson as Mrs Lovett, at English National Opera. The pair enjoyed huge acclaim for their performance of it in New York last year; ENO has grabbed it for a run, semi-staged. "John Berry of ENO was the only one who came to see it in New York, of all the people I asked," Terfel remarks. "I said that chances were that Emma would be champing at the bit to do it again, and he took the bull by the horns." With ENO experiencing turbulent times, hopes are strong that this starry show might begin to turn matters around.

Emma Thompson he describes as "truly magnificent. She is such fun in rehearsals – but she can floor you with a sentence. She's very clever in the way she thinks through what she's going to do on stage. It was a lesson in how to work. We had a week in the studio with just the two of us with the director and music staff, plotting all the way through her scenes with Sweeney and her magnificent opening aria, which she'd been working on for six months. Then I saw, through Emma's eyes, her singing with an orchestra for the first time, the New York Philharmonic. It was something new to her, yet she took to it like a duck to water. It was a sight to behold and a privilege to be there."

There is something wonderfully unjaded about Terfel's enthusiasm; despite all his years of experience, he has lost no capacity to be thrilled. Backstage after the New York performance, he says, "All Emma's friends came to see her, all these fantastic actors, including Julie Andrews. It was surreal for me, because some of my friends were there too – and I had Jonas Kaufmann to my left and Sting to my right, all laughing and talking about what they'd just seen. It was absolutely tremendous."

One review from New York grumbled that Terfel made the demon barber a "monster" instead of a "brute" – but Terfel has the best authority for his interpretation. "Sondheim has perhaps 60 years' experience in this business," he says. "And if he comes over to you and says, 'Bryn – darker' – then you've got to go darker. And if anybody says it's too dark… well, I was told by the composer to sing half of it through gritted teeth!"

First, though, comes Der Fliegende Holländer at the Royal Opera House, Terfel's most often-recurring Wagner role. The apparently un-dead anti-hero is condemned to eternity at sea, cursed by the Devil after making a rash vow. He is allowed ashore once every seven years to seek the true love that can save him. Wagner's scoreis a stunning musical evocation of fantasy and reality in head-on collision.

Bryn Terfel with Emma Thompson in the New York Philharmonic’s ‘Sweeney Todd’ (Chris Lee)

Terfel starred in this production by Tim Albery when it first opened in 2009, receiving rave reviews. Since then, he says, he has changed his approach thanks to "a moment of clarity" during a performance in Vienna. "Vocally something fell into place," he recalls. "It was something I did right on the stage; maybe I didn't give so much in the first monologue, which helped for the huge duet later on. Singing in Vienna also gives you a different match day: your adrenaline is different, your expectations are higher and you can be filled with trepidation because the Vienna audience can be quite tough. Put all that into the boiling pan and you have the ingredients for a soup that can lead you down a night of failure or a night of ecstasy. Now I'm feeling very confident and comfortable with it here, which is good – and hopefully no viruses will intervene. If we don't sing, we don't get paid and our livelihood is threatened."

It's not only viruses that can render a singer "indisposed". "I always joke," says Terfel, "that when Covent Garden offered me the Dutchman I said, 'Please give me a ship and please don't give me a rake, because I've had three back operations after being on a raked stage.' But unfortunately they gave me a rake and no ship. Still, if I'm faced with a rake it's up to me to swim more, to walk more and to do my Pilates exercises."

The back injury, he says, could in any case have originated much earlier: "It could have been a rugby game in north Wales, at school; it could have been all those hay bales I threw on to the trailer on the farm. But at a dress rehearsal of Don Giovanni, singing Leporello, I was picking up things that Don Giovanni was throwing around on a raked stage, and that was when it happened first. I went straight into hospital, had surgery immediately and had to miss all the performances. But, touch wood, it's been fine for the last decade."

Terfel's rise and rise began in 1989 when he won both the Kathleen Ferrier Memorial Award and the Lieder prize at the Cardiff Singer of the World competition. Most of all he credits supportive older colleagues with helping him up the ladder. "I had the greatest admiration for, and the greatest connection with [the Welsh bass] Sir Geraint Evans," he says. "He rang Sir Georg Solti once and said, 'Can you listen to this north Wales farmer's son?'" After making debuts in Mozart roles around Europe and the US, Terfel sang Jochanaan (John the Baptist) in Strauss's Salome at the 1992 Salzburg Festival – and the die was cast.

This year Terfel goes from Donizetti's L'elisir d'amore to Wagner to Sweeney Todd; and in summer, he stars in Fiddler on the Roof for Grange Park Opera. The beard he currently sports is to this end, he says: "It ties in nicely with the Dutchman," he remarks. New parts further ahead apparently include Boris Godunov, Mussorgsky's masterpiece with a gargantuan central role, for the Royal Opera House.

"I've had my Mozart time," he says, "I'm in the middle of my Wagnerian time now and I still try to share time with concerts. One thing I must do one day is Schubert's Winterreise; someday I'll be opening the score of that. And who knows, maybe there will be some more Russian opera on the cards."

Emma Thompson and Bryn Terfel are bringing Sweeney Todd: The Demon Barber of Fleet Street to the London Coliseum

He still has a wish list. He has long said that he would like to do a brand-new opera; indeed, for so long that it's high time someone wrote him one. Who would he like to commission, ideally? "I wouldn't know who to choose," he says, "but I like the work of Jake Heggie in San Francisco, and Mark-Anthony Turnage has done some great stuff." One rare opera that attracts him is Hindemith's Cardillac: "It's about a goldsmith who sells his jewels, then kills the people who buy them," Terfel says, with glee.

Last summer, a less welcome challenge arrived. Some of the press pounced when Terfel, whose 25-year marriage broke up in 2013, reportedly went on holiday with Hannah Stone, the 27-year-old official harpist to the Prince of Wales. Terfel, though keen to protect his three sons, eventually laughed off the intrusion: "If they really want to send a photographer all the way to the Costa del Sol to take a picture of my fat arse, that's their prerogative," he declares. To judge from the spring in his step and the glint in his eye, life is good. "I'm very happy at the moment," he confirms. "It's absolutely brilliant."

And so there is much to celebrate as he approaches his 50th birthday. He is planning a concert at the Royal Albert Hall in October to mark the occasion. "It is a significant moment for me," he says, "because I never thought I'd get to this point. Who knows what one's career is going to develop into? From Mozart into Wagner – I never thought that would even appear. But it's been a wonderful journey." With a voice and a heart seemingly big enough for the whole world, Terfel makes the most of everything that comes his way. Long may the journey continue.

Bryn Terfel stars in 'Der Fliegende Holländer', Royal Opera House, London WC2 (020 7304 4000) tonight to 24 February; 'Sweeney Todd', London Coliseum (020 7845 9300) 30 March to 12 April