What, you might wonder, would get a rich Russian in Switzerland really excited? Is it a particularly exclusive type of champagne brought over from France? Perhaps an overly extravagant chocolatier? No, what Iosif has stopped the car to purchase is a long-life cappuccino drink, served refrigerated in a plastic cup with a foil top at petrol stations across Switzerland. Disappointment. The cappuccino shelf is empty. There are only caffe lattes left.
"Valeriya," he says. "Could you ask the attendant; maybe they have some in the storeroom."
I can't help grinning. One of Russia's most famous stars, a face instantly recognisable to 140 million Russians, a woman whose every step in the motherland is followed by hungry paparazzi, is meekly asking a Swiss petrol station attendant if they have any plastic cappuccino cups in the back. But there will be no plastic cappuccinos today. The check-out girl gives a nonchalant shake of the head, while two bearded Swiss men in leathers look on in confusion.
In Russia, Iosif and Valeriya go everywhere with a driver and a minimum of two bodyguards. It's the possibility of behaving and being treated like normal people, without cameras and autograph hunters at every turn, which led the couple to buy a summer house in Anthy, on the French side of Lake Geneva, three years ago. Here, and in fact anywhere away from Russia and Russians, nobody has the first clue who she is. But this is something that, if their plans for the future work out as they want, will soon be something of the past, because Valeriya and her husband are intent next on making her a European superstar.
"I'm already established in my country," says Valeriya, as we sit down over green tea in the lakeside mansion. Two of her three children, from her previous marriage, loudly play tennis on a Nintendo Wii in the next room. I'm impressed with the tastefulness of the decor – the sleek furniture and pine floors and ceilings are a long way away from the kitsch with which most rich Russians deck out their houses.
"I want to go forward; not to stay in one place," she says. So this year, as she turns 40, is the year when Valeriya does Britain – a slickly produced single is already out, an album will follow in August and, according to Iosif, the ambition is that she should play Wembley or the Millennium Stadium "in about a year from now".
Born Alla Perfilova in the small provincial town of Atkarsk, Valeriya's journey to success was a long one. She left for the bright lights of Moscow as the Soviet Union was collapsing and won a place at Moscow's Gnesin Academy, a top-class music school. She met Alexander Shulgin when she was 21, and they started a professional and romantic relationship. Their first project, The Taiga Symphony, was recorded in English, and Shulgin decided that the name Alla was unsuitable for a Western audience because it sounded like Allah. Ever since, she's been Valeriya.
The English-language album flopped so she returned home to concentrate on Russia, and since then has apparently sold more than 100 million albums in her home country, which averages out at not far off one for every single Russian. I'm not sure quite how it's possible to calculate album sales in a country where even before the advent of downloadable MP3s nobody bought licensed albums, but there is no doubting that in Russia Valeriya has enormous Britney/Beckham levels of fame. On the whole she doesn't write her own songs, but she does have an impressive, powerful voice.
It takes a special kind of fame to pull off single-name recognition, all the more so because Valeriya isn't an exotic moniker like Prince or Madonna: it's one of the most common Russian names. But when I tell my Russian friends that I'm going to interview Valeriya, they all know exactly whom I mean. Even the old woman who guards the entrance to my apartment building in Moscow erupted in perhaps her first smile since perestroika when I told her I'd interviewed Valeriya.
As the 1990s wore on, Valeriya's marriage to Shulgin turned abusive, she says. Shulgin, she alleges, was a control freak who terrorised her and their three children and frequently physically abused her. She says that she dreamed of leaving him for years but didn't have the courage, putting on a show for the public of a happy marriage. Then, in 2001, she walked out, went back to Atkarsk with her three children, and spent a year living in a one-bedroom flat with her parents, vowing never to return to showbusiness again. She had no money, having signed it all away in contracts, and she says many people she thought were her friends deserted her.
"When I had a really hard time, not many people wanted to be close to me," she says. "When I came back again, they were suddenly 'so happy' to see me. It made me realise who my real friends are, and not many of them are in showbusiness."
But then she met Iosif, who won her trust, and later, her heart. A Jew from the dusty southern Russian republic of Dagestan, he had started as a teenager managing traditional bands that played mountain dances at local weddings, and came to Moscow aged 15 to start a career as a producer, eventually becoming one of the most successful in the business.
"I'd been aware of Valeriya for a long time," he says. "She beat one of the girls I was working with in a competition in the 1990s and I hated her. Every time she came on the radio I would turn the sound down."
She decided that this man was different to the other producers in the business, and chose to return to recording. To start with he was just her producer, and then they became romantically involved, marrying in 2004. The whole story is relived in detail in her 2006 autobiography, which sold hundreds of thousands of copies in Russia, and reads like a lengthy revenge missive against Shulgin, whose aggression and violence she goes over again and again.
"You know that she went on about it so much as a PR campaign," said a Russian journalist friend of mine darkly. "Half of all Russian women are beaten up by their husbands; it's a great way to reach out to female fans."
There may be some truth to this, and the book is certainly rather self-pitying at times, but there's no doubt that it took great courage for her to talk publicly about a problem that affects so many women in Russia and receives so little public attention.
"We have a Russian saying – 'If he beats you, it means he loves you,'" says Valeriya. "It's not true at all, and men who beat their wives are cowards." She says that she tells the women who write to her for advice that they shouldn't leave after one violent episode, but should let their husbands know that if it happens again, they will walk out. "It takes a lot of courage, and you think that if you leave you will have nothing. But in the end, you'll be better off."
In person, she has little of the capriciousness or arrogance one might expect from the rich and famous. She talks, in lightly accented English, with a sparkle in her big blue eyes and an impatient enthusiasm. Iosif doesn't speak English but frequently interjects in Russian to tell me just how great she is. The couple are playful and loving together, all their comments to each other infused with genuine affection. Throughout the day that we spend together, Iosif is permanently answering his iPhone. A call comes in saying that a Bollywood director wants Valeriya to do a shoot for an Indian film later in the year; the set-list for a private party has to be decided on; and someone enquires if she's available to play before a Russian boxer fights in Los Angeles in July. Valeriya takes just a single call during the day, and it's her mother.
"If even a single journalist found out my mobile number, I'd change it immediately," she says.
She's played at private concerts for Roman Abramovich "more than once", counts Vladimir Putin among her fans, and has even been flown in by the president of a former Soviet country to give a private concert.
"There were only about five people there," she says. "There were more people on the stage than in the audience." She only tells me which country it is after I promise not to reveal its identity in print, which is hardly surprising as I doubt the president in question would like it revealed that he spends the state coffers on flying in attractive female popstars for private gigs. It's these private gigs that provide the bulk of income for Valeriya and other Russian stars. Prigozhin tells me they get 20 or 30 offers a month, and usually accept around seven. Given that he says the average paycheque for such a performance is between $100,000 and $200,000, it seems like a pretty good earner.
To residents of Moscow, where even at 3am a plate of sushi is never more than a five-minute walk away, finding food on a Monday lunchtime in Anthy is surprisingly challenging. We jump into the Mercedes and speed into the village as we have only 20 minutes left before 2pm, when all the restaurants close. But when we arrive, the place looks closed anyway. Valeriya hops out into the rain and totters up the steps in her high-heels to check it out.
"Every day, sauf le lundi," she says dejectedly, getting back in. We drive up to another place, and again she jumps out to check the opening hours.
"She's always been very down-to-earth; never had any superstar disease," says Iosif to me. "I've seen how it affects some people; they become these impossible divas, but not her."
Finally we find a restaurant that serves Iosif's favourite, filets de perche, caught straight from the lake. Served with chips and a fresh green salad, it's as simple as it is delicious, the antithesis of the showy but disappointing fare dished up in posh Moscow restaurants. Afterwards we drive a few kilometres down the road to Yvoires, a picturesque and sleepy French village, to get a coffee. The rain is sheeting down now, and Valeriya produces a three-tone brown and orange umbrella, with frilly material cascading over its curves like petticoats.
"Look at this place," says Iosif. "It's so beautiful, and so absolutely without any showiness, or pomposity. We could have bought a place in Monaco, but it's a horrible place; everyone goes there just to show off. We'd have to put on a show the whole time."
The pair of them look utterly incongruous on the narrow cobbled streets of Yvoires, he in a brown jacket with a woven-in skull and crystal insets down the sleeves, her with her umbrella and a nifty Jean-Paul Gaultier jacket (the exuberant Frenchman has long been her favourite designer, she says, but only recently did they become friends). Amid the groups of anoraked pensioners on coach tours these two glamorously dressed Russians look like they've been beamed in from another planet. The pensioners stare in incomprehension – they have no idea who she is, but she's definitely not on a Saga coach tour.
"Mademoiselle, votre parapluie est très jolie!" calls out a small, wrinkled elderly woman browsing at a postcard stand.
Valeriya does a small curtsey of approval; Iosif asks her to translate.
"Everyone loves this umbrella," she says to me with a smile.
Her first single, "The Party's Over", didn't make any inroads into the British charts, but a remix is apparently doing very well in clubs across Europe, and the couple are certain that the forthcoming release of the album Out of Control will create waves. She's won the unlikely support and friendship of ex-Bee Gee Robin Gibb, who has spoken of his admiration of Valeriya and even sang backing vocals for her cover of "Staying Alive", the final track on the album.
"If someone had told me a few years ago I'd be singing with Robin Gibb, I wouldn't have believed them," says Valeriya. "Very few Western artists broke through to the Soviet Union but the Bee Gees were extremely popular. I always loved the songs."
According to the singer herself, when she has played her music for people in London, they are impressed. "The reaction I've heard most is 'surprisingly good'," she says with a smile. I have to agree. Frankly, I was expecting the English-language tracks to be appalling, and they are not at all bad. The production of the videos is slick and stylish, and the backing music has far more attitude than in her Russian-language songs.
"Most people in Britain who heard it were expecting it to be more cheesy," she says. Indeed, cheese is so deeply ingrained into the Russian musical scene that most of the country's superstars would not have a chance of making it in Britain. Even though the country's biggest male heartthrob, Dima Bilan, won Eurovision this year, his bemulleted head and shiny waxed chest seem more likely to induce spontaneous vomiting than record sales in the West. As for the old guard of über-kitsch crooners and divas, their multi-million record sales in Russia would translate to nothing more than derision.
I begin to wonder if her English-language songs only seem good because they are better than other Russian artists' efforts. Will "surprisingly good" be good enough to crack the British market? Valeriya and Iosif brush off Tatu, the faux-lesbian dance duo and the only other Russian act to be successful in Britain, as a "gimmick". But in today's world, lack of gimmicks might be their main problem. It's difficult to see just who would be the target audience of a 40-year-old, previously un-established singer who sings pop songs. And did nobody tell her that the line "You're not my boogie woogie and sure not my sweet Valentine" was probably best excised?
"Today everyone shows their body," says Iosif, as the couple drive me back to my hotel at the end of the day. "But she advertises a healthy way of life." Valeriya doesn't smoke, hardly ever drinks and is the mother of three children. But without the intrigue of teenage lesbians or a Pete Doherty or Amy Winehouse personal saga, it's unclear what will keep a 40-year-old Russian woman in the headlines of the British tabloids and consciousness of British fans.
Still, it's not going to stop them putting a lot of money and effort into trying. And if she ever does make it to Wembley, I might just be there in the front row, cheering her on.
'The Party's Over' is out now on Nox Music. The album, 'Out of Control', will be released in August