In the years since the Pet Shop Boys' -debut single, West End Girls, -became a global smash, selling 1.5 million copies, Neil Tennant and Chris Lowe have sold 50 million -albums and had 39 further hits. The statistics alone are impressive but, perhaps uniquely for such a formidable pop act, the band has successfully and effortlessly moved between mass and niche culture, art high and low. The current tour for Yes, their latest album and arguably their finest work of pure pop in years, includes a spectacular stage show featuring enormous stacks of white cubes that nod to Rachel Whiteread's Embankment installation in the Turbine Hall of London's Tate Modern gallery. It's a theme that has run throughout their career. The Pet Shop Boys have worked with the late Derek -Jarman, written a feature film -starring -Barbara Windsor called It Couldn't Happen Here and collaborated with the likes of Liza Minnelli, Rufus Wainwright, Zaha Hadid, David Bowie, Johnny Marr, Bernard -Sumner, Tina Turner, Dusty Springfield, Sam Taylor-Wood, Elton John, Robbie Williams and Kylie Minogue. One of their most -successful and well-realised projects in recent years has been their superlative score to Sergei Eisenstein's -Battleship -Potemkin. You wouldn't have got all that from Wham! or -Kajagoogoo, who formed in the same year as the Pet Shop Boys. What English groups have been so ambitious and broad-minded, -easily crossing the boundaries between music, art, film, fashion and theatre? The Pet Shop Boys and their body of work are a legacy of the post-punk era rather than glossy 1980s pop milieu. Since the band's inception, Tennant and Lowe have continually used their intellectual ideals (born in the radicalism of the late 1970s) and sought to embrace new technology and ideas in art to keep -moving forward. After establishing such a track record on their own terms, why did the Pet Shop Boys choose to collaborate so closely with Brian Higgins's Xenomania - one of the hottest pop production houses on the planet - for Yes? There's something in Tennant's smile that suggests it was done, in part, as a provocation, to confound people's expectations of what a Xenomania-produced Pet Shop Boys record would sound like. "Just to give you a negative spin on the new album, there are people who have said: 'I was expecting it to be like Call the Shots by Girls Aloud meets Delusions of Grandeur by the Pet Shop Boys.' They said that about the new single," he explains. "But we didn't think: 'What's our favourite record by Xenomania and what's our favourite Pet Shop Boys record? Let's try and cram them together.'" "Somebody told me they thought it would be West End Girls with Push the Button," chuckles Lowe, whose droll humour is at odds with his unmoving, taciturn stage persona. In fact, the Pet Shop Boys had wanted to work with Higgins for some time, but friends and their own material conspired against them. "Firstly, we heard that New Order, who we know, were working with them and thought: 'Bernard's got in there first,'" Tennant says. "It's always been a strange thing with the Pet Shop Boys and New Order, and especially Bernard Sumner, in that we've had similar record collections and liked the same things. It's a Sin and Bizarre Love Triangle are both inspired by the same German record, though I can't remember which one now. That's the first reason. "When it came to the album Fundamental, we'd already made the track Numb with Trevor Horn, and we could just imagine him doing a really amazing job, so we went with him for the whole album. With Yes we wrote loads of songs and a lot of them were really up pop songs." It simply seemed like a logical fit to collaborate with the creators of some of Girls Aloud and Sugababes' biggest hits. Lowe says that part of the pleasure of recording Yes was being part of the "whole pop experience" that is the Xenomania hit factory. "Girls Aloud were hanging around. You'd go into the sitting room and they'd all be there with their laptops. We had lunch with Alesha Dixon." "She's very nice," Tennant interjects. The experience reminded the Pet Shop Boys of the 1980s music scene, when they were pivotal figures in nightclubs, the Top of the Pops studio and European music festivals. "We once flew back from an Italian pop festival, and on the plane was The Smiths, The Style Council with Paul Weller, Depeche Mode and Spandau Ballet," Tennant says. "Dave Gahan was making jokes about the plane crashing." Back in London, the Pet Shop Boys were a constant presence on the music scene - and not only in their 1980s heyday. "In those days, the Limelight had opened," says Lowe. "And everyone was always in the VIP bar. George Michael, Gary Kemp, Patsy Kensit. The last time this happened was with Britpop with the Groucho Club. Also in the early 1980s there was the Star Bar at the Camden Palace. Everyone was there." The same was so of the Hacienda in Manchester, where Tennant and Lowe found themselves in the early 1990s. It's remarkable that the pair have been present in so many of Britain's most fertile musical scenes. "We're like Andy Warhol aren't we?" laughs Lowe. However, Yes once more underlines the fact that the Pet Shop Boys have far more to them than a pair of well-connected 1980s -bohos. S-ocial commentary has always been a strong suit of -Tennant's lyricism, whether through the exploration of Catholic guilt in the sublime It's a Sin or exploitative relationships in Rent. "'I've got the brains, you've got the looks, let's make lots of money' from the song Opportunities - that's about Thatcherism," Tennant says. "I think pop music works as a commentary to society and to attitudes, and that's the Pet Shop Boys," he says. This time around, songs such as Beautiful People and Love Etc are explicit digs at celebrity culture, something that has taken even the astute pop observer Tennant by surprise. "We wrote a song called Shameless for the B side of Go West that was about celebrity culture, which we thought then had reached its -zenith. Actually, it had barely started. That was 16 years ago. "I like doing that. I like writing songs with an element of humour about them as well. So there's a whole strand of the Pet Shop Boys that's social stroke political commentary." It's there, too, in Building a Wall, which Tennant says addresses "the homogenisation of everything. All our towns have all the same shops. I sometimes find Britain stifling because of that. There's this monoculture everywhere. I'm hoping with the recession... I've noticed it's clearing out the crap". Tennant says that Building a Wall is a classic Pet Shop Boys song in the way it brings together "allusions and references while not really having a clear linear meaning. They're the ones I tend to like. I don't always like obvious meanings. At the same time, it's very satisfying when you take something and see it through to the bitter end. My favourite poem has always been The Waste Land by TS Eliot - all these different voices and allusions. Even a song like West End Girls was supposed to be like The Waste Land because it's got different voices in it." Their blending of the political with arch aesthetics, of high and low culture, of high glamour and simple pop hits stems, according to Tennant, from the group's origins in the post-punk era. Indeed, could the late, great John Peel's maxim that The Fall were "always different and always the same" be applied to the Pet Shop Boys? "One hundred per cent," Tennant says. "We're always trying to do something different, but it's always going to be a bit the same because it's the two of us." He explains how a post-punk ethos of "rip it up and start again" has -always shaped the band's music and performance. "I think most people don't -realise this. Punk was great, but it was a bit limiting. When you took punk ideology and applied it without any fear of market or of fashion, that's where interesting things happened, and that's where the Pet Shop Boys come from. In a way, it's even where Annie Lennox has come from, but it's not where Take That have come from. That's why there's an ideological division -between modern pop of that kind and other pop." It's a mentality that still shapes how the Pet Shop Boys write, and it explains the simplicity of tracks - the crisp bounce of Love Etc and the carefree, guitar-flecked pop of Do You See Me Coming, which echoes the work Tennant did with Electronic's Bernard Sumner and Johnny Marr. "I think anyone who thinks about the meaning of their music has a relationship to punk because punk was essentially about meaning over form, ability and technique," Tennant says. "The thing punk didn't do was play too many notes, and there's a wonderful economy to it." It's that economy that is still manifest in Yes, the band's collaborations and their live performances. Tennant and Lowe continue to move forward and refuse to sit back - as they undoubtedly could easily do - on cosy 1980s nostalgia. As Tennant explains, it's a punk thing: "I think people of our generation, the post-punk generation, as they've got older they still have their roots in loving David Bowie when they were teenagers and being inspired by punk even if they didn't make punk records. There's also the thing of saying no, and not always being agreeable."