In the post-punk Eighties, the idea of a prog-rock revival was an unspeakable thought, and Yes were too far beyond the pale even to be considered the enemy. Their prog-rock excesses had left them stranded like a brontosaurus in a tar pit, relics of another era. And yet today I find myself in a luxurious lakeside hotel in Montreux, waiting to meet these survivors of a world where bolting classical orchestras, primitive synths and rock guitars into grandiose conceptual suites seemed like the future of pop.
This clean, quietly-rich Swiss Alpine resort is where several Yes records were made, and where sometime keyboardist Rick Wakeman spent the Seventies as a neighbour to James Mason, Charlie Chaplin and David Niven - an English tax-exiled aristocrat who punk would surely not ever let return. Yes have played the Jazz Festival here so often that when they do so again tonight guitarist Steve Howe will be gifted a special guitar, like a rock carriage clock. But the musical bus passes won't be needed yet. Listen to Radiohead's classical string-soaked, intricate Kid A, soon to be released albums from Elbow (big Yes fans) and Muse (creating a classical-rock fusion that practically is Yes), or even the Flaming Lips' last, expansive concept album, and the dinosaurs are breathing again. Yes, like it or not, are back.
"What's happening," Wakeman gratefully agrees, "is that young people are opening a lot of drawers and finding things that were buried, and going, 'What's this ?'. Prog-rock used to be the porn of the record industry, and people would almost ask for it in a brown paper bag. But bands are stealing bits of it now, because they want to progress. Bands like Muse, Super Furry Animals. Radiohead started it 10 years ago - I know they hate being called prog-rock, but they've taken a lot from it, and opened things up an amazing amount."
The genuine article prog-rocking thing, though, is very different to that of young pretenders like Thom Yorke. Even at their Seventies best - heavily represented on the new 35th Anniversary Collection - Yes sound ponderous in their adoption of classical motifs and perilously light on tunes. It largely bears out punk's prejudice, whatever a new generation might think.
Meeting them is much better value than listening to them. They currently comprise the five core members of a line-up that has constantly mutated. I meet the likeable, chatty Wakeman in a bar, encounter the co-founding bassist Chris Squire, all business, in his hotel room, and come upon the singer-songwriter Jon Anderson - small, shakily egotistical and eerily intense - in a vast, empty hotel lounge, long after midnight (Steve Howe and the drummer Alan White complete the quintet). As unlikely a band as you could ever meet, their tales of hubris, madness and symphony-scale musical differences could fill a triple concept album.
When Anderson thinks back to his early days, though, what you feel first is the thrilling ambition with which Yes started. A fan of Elvis and the Everlys when he left school in Accrington in 1958, aged 14, the heady atmosphere of mid-Sixties London made him yearn for something more transcendent. "In 1967, especially, music just blew up," he recalls. "Jimi Hendrix, Sgt Pepper, Pet Sounds, Frank Zappa - all those things went boof! in that year, and I jumped into that. I also started listening to Stravinsky, and within a couple of years of starting Yes in 1968, Sibelius too. I enjoyed listening to commercial pop music, I always have, but having tasted the fruit of those composers, from then on I didn't want Yes to just be doing mainstream rock structures. I wanted to push into more bizarre worlds."
The Who's rock operas were another influence. But the sense of expansive adventure which new bands love in Yes is, Anderson reveals, rooted in more unnerving, personal territory. Spiritually confused even before he joined Yes, Anderson's quest for "self-realisation" was the motor for their earnestly philosophical lyrics and exploratory spirit. But when, as we sit alone in our hotel's huge, deserted lounge, he starts to tell me just how far he's gone in that search, for the first time ever in an interview I feel a genuine chill. He starts to describe meeting an unearthly little girl and large Jamaican man in Las Vegas after a Sinatra concert in 1977, deciding they were angels, and seeing walls melt as God was revealed to him. Something in his tone makes me fear him. "The angel said he was very happy with the work I was doing," he calmly concludes, "and prophesied that in the 21st century I would still be singing the same songs." We could all have guessed that. But easy as it is to smirk, Anderson is in deadly earnest.
His tendency to worrying excesses reached its musical zenith after the commercial success of Fragile and Close to the Edge, with 1973's landmark double concept album Tales from Topographic Oceans. An eco-philosophical, quasi-classical work comprising four side-long, shapeless "movements", even Radiohead would have the plug pulled on them for suggesting such lunacy today. But, in 1973, it got to number one. Wakeman and Squire both still shudder at the memory.
"Jon was really diving in the deep end, and I didn't think he should be doing it," Squire says. "He was very certain in his mind of what he wanted to do, and I don't think any of [the rest of] us were. It required a lot of after-hours salvaging of wherever we'd gone that day. I found myself in the studio six or seven hours after he'd left, till four in the morning. But," he half-laughs, incredulously, "die-hard Yes fans love it."
"Yeah. Well." Anderson speaks sulkily of his partner's misgivings. "There's a lot I could say off the record about who gave 100 per cent to it. But I know what I was doing. I was trying to create something that would be everlasting. Now, who's to say we shouldn't have tried that? It was easy for the record company to say we screwed up. Of course we screwed up, from their point of view. From an artistic point of view, at least we jumped."
It's this sense of overreaching, of leaps of faith that fell short, that may turn out to be Yes's most valuable example to bands today.
"The Seventies were fantastic," Wakeman says, "because musicians had the freedom to make mistakes. And we did, because we were trying to be progressive, and trying to come up with new things, and we'd got nothing to gauge it by. We've now got 35 years' worth of material. Probably three hours really works. The rest of everything we've done was getting there."
"I always overreach, because I don't know my limits," Anderson considers. "I don't have boundaries in my head. So I don't see why we can't have this room full of 3-D inter-dimensional energy holograms, performing in front of us right now," he complains. "Probably there are, we just can't see them. In 10 years' time anyway, I think we'll be able to manufacture them for gigs. So I have no lack of visions. And I can understand Rick and Chris's trepidation, because they live in a denser world. Rightly or wrongly, I float around a lot. I don't like to be in the world's density all the time."
Punk helped put an end to such high jinks. The band are philosophical about the movement now. Questioned about the period, Squire reveals an unusual friendship. "Strangely enough, I got to know Malcolm McClaren quite well, and I asked him if he felt outwardly hostile to us when he put out The Sex Pistols. He said, 'No, I love Yes. It was just a business move.'" Wakeman blames the Eighties' obsession with fashion for Yes's eventual fall: "I had a lot of friends in the media, and suddenly, they didn't want to be seen with me, in case they lost their jobs. It hurt. It bloody hurt a lot."
The band have fractured and reformed many times since. But after decades of feuding and, some say, financial mismanagement, these three at least seem resigned to being in Yes now.
When I suggest to Wakeman, though, that they're a little absurd, he says this: "It is absurd that there is a band of guys ranging between 54 years old and 60 years old who are getting up on stage tonight, dressing up and prancing around. But that's what you do. Rock'n'roll is a little absurd, from start to finish."
'The Ultimate Yes - 35th Anniversary Collection' is out this week on Warner