Hay Festival 2012: An interview with Bryn Terfel But often, it's sheer stamina that a singer needs to negotiate Wagner's gargantuan structures. "It was George Bernard Shaw who said Wagner has sublime moments but terrible half hours," Terfel nods. You might get 40-minute sections like the second act of Valkyrie, when Wotan recalls what happens in Das Rheingold to his daughter. It can go pear-shaped unless you're totally concentrated and are taking in everything that's happening around you. In New York, the stage set [by Robert Lepage] was these planks that kept moving, so you had the extra difficulty of moving around the stage. Despite his feats in the world's great opera houses, it's typical that Terfel should single out his first-ever performance as Hans Sachs in Welsh National Opera's 2010 production of Wagner's Die Meistersinger as one of his most meaningful accomplishments. It was in Cardiff, and the cast was 60 per cent Welsh-speaking. It's the first time I've walked into a rehearsal room speaking my mother tongue, which in itself was a breath of fresh clean air from the Welsh mountains. Singing Hans Sachs is always a milestone, but I was happy to be part of such an achievement, not personally but as a company. Rehearsals for the Royal Opera House Ring begin in August, but meanwhile there are different kinds of business to take care of. He's promoting Wales Air Ambulance, one of three charities he supports, and later in the day he'll be recording radio slots for it and launching his specially written charity single, Guardian Angel. The following evening, he was due to host a concert at Prichard-Jones Hall at Bangor University, performing alongside promising young singers and musicians selected for his Bryn Terfel Foundation. And coming up fast over the horizon was his performance at this year's Hay Festival, helping to mark its quarter-century. Terfel attended the first Hay Festival in 1988, intrigued by the notion of somebody being audacious enough to stage a cultural gathering in the shadow of the Brecon Beacons. "The format is incredible, and people from such diverse backgrounds visit this wonderful little enclave in the middle of Wales," he reflects. At the first festival I sang a concert of Welsh songs. I was very curious about where it was and the idea they had. The Hay Festival has burgeoned into an international franchise which runs 15 festivals across five continents, and it's hardly to be wondered at that Terfel often finds himself bumping into Hay alumni. It's great to see it going from strength to strength. I keep meeting people who have been there. I did Garrison Keillor's radio programme, A Home Prairie Companion, and [author] Frank McCourt was on it, too. He's a Hay veteran. I met Salman Rushdie coming out of a theatre in New York, and he was talking very fondly about Hay. He subsequently came to the Ring at the Met, so there are all these little things connecting the jigsaw. This year, Terfel is planning a 70-minute performance, which will be "a combination of some lieder, some operatic arias and probably me looking back at my career as well. I've been singing songs by an American baritone who was half-Welsh, John Charles Thomas, so I'll probably do some of his repertoire, too. After that he faces the four-day BrynFest at London's Southbank Centre in July. This has its roots in Terfel's Faenol festival, which was staged on the Faenol estate near his home from 2000 to 2008, before stalling through lack of funding. It irks him that sponsors haven't been willing to stump up to get the show back on the calendar, but he hopes the London version of it may trigger renewed interest. Terfel is unique in being able to perform opera, Broadway songs and folk ballads with total conviction, perhaps because he treats each on its own terms and refuses to over-analyse. As he told me once before, "I don't understand people who think opera singers shouldn't sing musicals, because all the same rules apply for every type of singer." After a plan to stage Sondheim's Sweeney Todd fell through, the South Bank suggested adopting his Faenol formula of separate opera, music theatre and rock nights, with some stout Welsh choral singing for good measure. Thus, the Golden Age of Broadway night will comprise songs by Rodgers & Hammerstein, Cole Porter and Lerner and Loewe. In an Evening of Opera Classics, featuring Verdi, Donizetti, Puccini and Bizet, Terfel will be joined by soprano Oksana Dyka, American tenor Lawrence Brownlee and Georgian mezzo-soprano Nino Surguladze. At the Wales: Choir of the World event, a 500-strong male voice choir will sing, among other things, the world premiere of Karl Jenkins's A Hero's Journey. The rock night is in the hands of Gruff Rhys, from Cardiff rock band Super Furry Animals. "It was really complicated to connect with all these artists," he reflects, "but the final line-up is looking wonderful." My last glimpse of Terfel that day is him standing in front of a crimson Wales Air Ambulance helicopter which had just whirled down onto the lawn of a country hotel, sending sheep scattering. He'd changed into a sleek grey suit, was surrounded by dignitaries, and was beaming into assorted camera lenses while brandishing copies of his new charity single. If Wales ever needs a president... Bryn Terfel performs at the Hay Festival on June 8; BrynFest (July 4-7) is part of Southbank's Festival of the World with Mastercard; the "Ring" cycle opens at the Royal Opera House on September 24, 020 7304 4000