The Pet Shop Boys' world tour hits London later this month. JEREMY LANGMEAD says that behind the stunning stage show, the vibe is more snacks and naps than sex and drugs

ROCK 'N' DROLL

We all know what pop stars get up to on tour: drink, drugs and group orgies. Nonstop. That's - woah! - rock'n'roll for you. Leather pants, tequila slammers, burly bouncers . . . oh man, it just goes by in a, like, blur.

Except it doesn't any more. Not so many pop stars drink themselves into oblivion or overdose themselves to hell now. Many of them live to a ripe old age and still churn out the hits. Thank God, otherwise we might all have been denied the pleasure of Sir Clifford being a potential No 1 this Christmas.

Yet some of these more mature pop stars you just can't imagine hitting the road, kipping on the tour bus, joshing around with the roadies and post-gig partying into the early hours night after night for months on end. Take the Pet Shop Boys - Neil Tennant and Chris Lowe - the duo who gave the world disco lyrics it wasn't embarrassed to repeat. They've been together 18 years, made seven studio albums, had 33 Top 30 hits and three world tours, but now that they are both home-loving fortysomethings with a penchant for expensive art (they hang out with Sam Taylor-Wood), high-tech kitchens (Lowe's has been featured in Elle Decoration) and country cottages (Tennant's is in County Durham, Lowe's near Rye), how would they take to roughing it again with a 45-man crew for the first time in eight years?

The Nightlife tour has taken 12 months to prepare. The set is by the architect Zaha Hadid, the costumes and staging by Ian MacNeil, the theatre designer responsible for An Inspector Calls. The backing singers are all from America, the rehearsals took place in West Palm Beach and, due to the promoter Harvey Goldsmith's financial spot of bother, the whole production will lose the band about £750,000. Luckily, according to MacNeil, the Pet Shop Boys are the most laid-back and unflappable people he has ever worked with.

It certainly seems that way when the pair appear in the lobby of the Four Seasons hotel in Berlin. It is 5.30pm, three hours before they are due to go on stage. Lowe is wearing a long-sleeved navy T-shirt and jeans, Tennant a dove-grey hooded Jil Sander top. Although they only arrived in the city an hour before, Tennant has already nipped into the nearby Guggenheim Museum to see an exhibition. They are both chatty and friendly, far removed from the aloof figures they like to portray themselves as. Their tour bus, which now takes them to the show venue, is comfortable but not luxurious. There are red couchettes along each side and a leather-seated area at the far end with a television, a pile of videos and a few leopard-skin scatter cushions. There is a bowl of fresh fruit and a couple of bottles of red wine. It's all very civilised.

Two hours before the concert is due to start, backstage is a hive of activity. A temporary canteen has been set up where the caterers have been preparing dinner for the crew since eight that morning. Along the corridor is one of the three dressing rooms where two wardrobe assistants have spent all day washing, ironing and restitching the costumes: hanging proudly is a bizarre mix of red and black sombreros, dustbin-liner pantaloons and four yellow builders' helmets. Adding a few final touches is Jeffrey Bryant. He is from Wales and in charge of putting the backing singers into their stage outfits. A Welsh dresser. That's very Pet Shop Boys.

Tennant and Lowe are ensconced in their large, sparse dressing room. The latter, who has just gobbled down a large plate of roast chicken, roast potatoes, peas, carrots and stuffing ("You want stuffing, Chris?" asked Rosie the caterer, to much amusement) is having a catnap on the leather sofa. Tennant is nibbling on a pastry and the occasional chocolate plucked from a selection placed in a nearby glass bowl. They are almost a caricature of their stage personas: an unlikely combination of Joe Orton and Noël Coward.

The pair have only two costume changes in the show and the most startling look they adopt is the one they have used in their most recent videos: big black coats, big black eyebrows, sunglasses and strange tufty Beethoven hair. Their straggly blond wigs are sitting on the dressing table behind them. They cost £1,200 each.

When the Pet Shop Boys formed in 1981, they dismissed the whole rock'n'roll idea of dressing up as not very them. They didn't want to look silly. Now that almost seems the point.

"We decided to start dressing up as a reaction to the current boring, Boyzone natural look. In the 1980s it was the complete reverse," says Tennant. "Now we definitely want to have a bit of fun." It's 7.30pm and time for them to get into their costumes. Outside their dressing room, four enormous backing singers are wandering around in scarlet tops and baggy trousers; Sylvia Mason-James, the additional vocalist, is practising her scales; and Dainton, the band's big friendly giant of a PA, is making sure nobody bothers the boys while they get ready.

Fifteen minutes before the show and there is no sign of stagefright. Tennant says that he always gets a bit tetchy at the beginning of a tour, but once the glitches are ironed out, he's utterly relaxed. Not as relaxed as Lowe, who is once again napping on the sofa. You would never guess that a few feet away are six-and-a-half thousand screaming German fans. The first chords of the opening song strike up and the boys are still in their dressing room with its neatly arranged wine glasses, throat lozenges and homeopathic medicines. It looks more like a nursing home than a rock venue.

"Come on," says Tennant, "we're due on stage."

"Do we have to go now?" pleads Lowe. "The music plays for ages before they can see us." Tennant gives him a withering look and they swish downstairs, led by Dainton, in their fitted jackets and billowing culottes. It's all very Dior New Look.

The show goes extremely well and the Berliners respond enthusiastically to the two-hour set - with a civilised 20-minute interval, naturally - that covers 21 of their greatest hits. There is the added excitement, too, of a fainting fan - not a bad feat to be able to incite such blood-draining devotion at 45 years of age. Lowe stands throughout the concert, as is customary, motionless behind his keyboards, while Tennant bounds energetically all over the stage as he belts out the songs. At the front of the crowd, a strange assortment of die-hard fans are bopping away happily in tall pointed hats and giant black eyebrows. Tennant calls them "Petheads", after the loyal Grateful Dead fans known as Deadheads.

As soon as the three-song encore is over, the sweat-drenched duo rush back to their dressing room and the riggers and carpenters, who only started putting up the set at 3pm that afternoon, get to work dismantling it again. Upstairs, it's champagne all round. Even Lowe seems animated with the excitement of it all. Wigs and brows are removed, friends pop in to congratulate them, and then the pair have to do a dreaded meet-and-greet with 40 competition winners. As soon as the last of them has been bustled out of the door, Lowe, whom some might suspect of narcolepsy, is back on his sofa, huddled under his coat.

An hour later, everyone arrives back at the hotel. Lowe - surprise, surprise - goes straight to bed, but Tennant and the rest of the band head for the bar. The Pet Shop Boy orders red wine - he's on a food-combining diet - the others opt for cocktails or more champagne. A drinks tray even gets knocked over. Things are looking a bit more rock'n'roll. At about 2.30am, Tennant eventually heads off to bed, too. About half an hour later, so do most of the others.

A lot of alcohol appears to have been consumed and the bar bill must be huge - as it should be after a pop group's been knocking them back into the early hours. I nosily take a peek to see how much it came to: £250. Bless. It's not exactly of Keith Richards proportions, but I bet it's a lot more than any of boring young Boyzone's has ever come to.