Although, when he first came to work in Wales, Stein jokingly admits he had "problems even spelling Cardiff", you'd have thought he'd have got used to the weather by now. Grimes is, after all, his fourth production for Welsh National Opera in 13 years, and he's only ever done seven operas in his entire 35-year career. "You know, I'm a straight theatre director," he insists first thing, "and I want to be considered as this, not as an opera director. Opera is, for me, a kind of tourism."
And the reason he chooses to spend most of his "holidays" in Wales is that WNO offers the perfect package: choice of repertoire; extended rehearsal periods (seven weeks for Grimes); the final say in the casting; above all, "a team of people who do what they do, because they want to do it; who see the work, not as a devoir, a duty, or only to earn money - because, believe me, to earn money in this company is very hard! - but as a chance to... explore."
Initially, though, it took much wooing by WNO's then managing director, Brian McMaster (now of the Edinburgh Festival), to coax Stein to Cardiff at all. It wasn't just that, as artistic director (1970-85) of the Schaubuhne, Berlin's acclaimed theatre collective, Stein had his pick of projects the world over, never mind Wales. It was more that he had already washed his hands of opera twice over, once as a spectator, then as a director. As a child growing up in wartime Berlin, his earliest theatrical experiences were all of going to the opera: "First Peterkins Mondfahren - `Little Peter's Moon Voyage', a kind of children's musical - when I was three, in 1940, just before the bombing started. Then Humperdinck's Hansel und Gretel - this, it's clear, is what a well-educated young boy has to hear! Then Freischutz. Then Aida."
He went on going during his teens in Frankfurt, during his student years in Munich. But then a fat lady sang, and it was all over between him and the opera. "I remember very well, it was after a performance of Strauss's Elektra, with Astrid Varnay, that I decided: `Basta! I don't go to opera any more.' She was too old, too fat by then. I could no longer stand the Diskrepanz between the music and what was happening on stage, where a fat woman of about 58 years fakes to be a young girl and to make a dance in which she cannot move. Come on, I said, I can buy a record for the same price as a ticket, and listen at home. And after that I never came back to opera - until I was asked to direct it. So I was very strict when I was younger," he chuckles. "Too strict. Now I am ready to do everything... Anything! Just call!"
The call, when it first came though, was to direct a complete Ring, with Solti, at the Paris Opera. But the cycle was cut short after Rheingold (in 1976), when Stein pulled out, frustrated that he had to rehearse with understudies - "the big stars weren't due in until the dress rehearsal! For an opera director, it's OK maybe, but, for a theatre director, it's appalling." No wonder it took a decade for him to be lured back to opera. And when he was, it wasn't solely McMaster's promise of ideal rehearsal conditions that won him over ("with all the singers always there, so together we can explore something, work something out"), but the piece on offer: Verdi's Otello.
For the other lesson he'd learnt in Paris was that he could only care for operas where the text itself invited the involvement of a "straight theatre man". And, heresy though it may be to Wagnerites, he felt this just wasn't true of The Ring. "I loved the music. Or, let's say, I found it very interesting - sometimes crazy, sometimes kitsch, always powerful. But the libretto! Wagner's words are so lousy that, if I read or hear them without the music, I simply have to laugh!" And he does. "A very Homeric laugh", if he says so himself.
Otello clearly is something else. Not just because its text is taken from Shakespeare, but because it is, says Stein, "a programmatic piece, where, after a pause of 10 years, Verdi came back to opera as an old man with the explicit intention of introducing theatre into opera. He knew it was a paradox - it doesn't work 100 per cent - but he wanted it, absolutely, and therefore he chose Shakespeare as the icon, the essence, of theatre. And indeed he succeeded quite well." Though not as well, he feels, as in Falstaff, Verdi's next and final opera (and Stein's second for WNO), "where, if you listen on CD, it is only 60 per cent as much fun as when you see it on stage. Unlike Nabucco, say, which is much better to hear than to see."
So Stein now restricts himself to pieces where a "straight theatre man" can add his 40 per cent, where, as he modestly hopes, "at the end the singers say: `Oh, yes, you helped us by your staging'." For that's his aim - "to help the singers sing better and to help the audience listen better. This more and more becomes my joy, to make the staging work, so you can even understand the structure of the score." Anyone who saw his 1988 Falstaff, for example, will recall how simply, yet skilfully, he choreographed that final, fun-fuelled fugue so as to articulate each bubbling, bobbing, jostling vocal strand.
The search for suitably theatrical scores brought him in 1992 to Debussy's Pelleas, a staging that was planned to mark Stein's operatic comeback in Paris but was ditched in the wake of Barenboim's dismissal from the Bastille, and ended up at WNO on the rebound, though with Pierre Boulez still on board. "I think it was really a gift from Mr Boulez to do the production here," says Stein. The willingness of the great composer-conductor to accompany Stein's staging on tour, appearing in the pit on wet Thursday evenings in Bristol, Birmingham and Southampton, represented a double coup for the Cardiff company. The two collaborated again on Schonberg's Moses und Aron in Amsterdam in 1995, since when Stein's only other opera has been Wozzeck in Salzburg two years ago.
Given the debt Britten's opera so obviously owes to Berg's, Grimes seems a logical follow-up, though Stein insists it's coincidental. He was originally asked to do the piece in Vienna, but turned it down, partly as the casting was already done (and he couldn't see how it could work with the given tenor), partly as he felt he could only do Grimes properly with English-speaking singers - "people who know exactly, also in a little bit an ironic way, what it is about, this weather and this rain, and this special relationship to nature and the sea, and the fighting with that, and so on." That said, he was shocked to find "how strangely English singers behave when they sing their own language, trying to ennoble it with a kind of rostrum of operatic behaviour, so that it becomes a little bit pompous, as if it would be an oratorio or I don't know what." The "plum in the mouth" style jars all the more in a work where, even if the text is sometimes overflowery and poetic, "the themes are very direct and concrete, and it's about the lives of ordinary people - fishermen, not Kings and Queens".
What gives the work its "special fascination", though, is how precisely rooted it is in the soil and sea of Aldeburgh, the Suffolk fishing village where Crabbe's original poem is set, where Britten settled and founded his festival. As a self-confessed provincial ("Germany is all made up of provinces, they have no capital"), Stein particularly admires the way it draws the universal from the provincial, how one tiny dot on the map can harbour a drama of global import.
Naturally, he visited Aldeburgh, but as for re-creating it on stage, forget it. "Realism in theatre is very difficult nowadays," he observes, "when you can push a button, pouf!, and have virtual reality in your own home." The answer is to isolate elements that really count - in Grimes's case, Aldeburgh's role as a fishing community. "So the only real things on board - sorry, on stage! - are the boats... they are made in Aldeburgh, and they are my joy!"
`Peter Grimes': New Theatre, Cardiff (01222 878889), 15, 20, 24 Feb (live on Radio 3); Apollo, Oxford (01865 244544), 2, 5 March; Hippodrome, Birmingham (0121 622 7486), 23, 26 March; Sadler's Wells, London (0171 863 8000), 30 March, 3 April; Empire, Liverpool (0151 709 1555), 6, 9 April; Grand, Swansea (01792 475715), 13, 17 April