Strange things have been happening in the British pop charts of late (and no, we're not talking about Jedward's failure to clinch number one). Wade through the usual Lady Gaga, Florence and the Machine and Paolo Nutini albums, and there in the No2 spot is Andre Rieu and his album Forever Vienna. The cover alone stands out: a couple dance dreamily around a ballroom. The man, dressed in a traditional tailcoat, holds his partner in an elaborate swoon. She, wearing a swishy ball gown, has her neck bent in the direction of the window. They are waltzing - to the tune of the Dutch violinist Andre Rieu and his Johann Strauss Orchestra.
Forever Vienna, a compilation of traditional waltzes, has beaten Hot Chip, Corinne Bailey Rae, Journey and Peter Andre, all of whom have had new albums out this week. Not only is it the highest-charting orchestral album in history, but it is also the first time a CD of 19th-century music has appeared in the charts. So what on earth is going on? The waltz revival has been gathering pace ever since Rieu, a conductor's son from Maastricht, started blowing the cobwebs off the form with his elaborate 50-piece orchestra. Formed in 1987 with only 12 members, the Johann Strauss Orchestra soon earned a reputation for its lively, emotive performances, with Rieu being named "the king of the waltz".
Not for him drab musicians all in black. Instead his dapper players perform in full tailcoats and bright, slightly daring ball gowns. As their popularity grew, so did their stage sets. During their recent world tour, a life-size reproduction of the Viennese Imperial Schönbrunn Palace dominated the stage, complete with two ice rinks, two fountains and a huge ballroom dance floor. But the pièce de résistance is Rieu himself, who leads the dances from the front using his 1667 Stradivarius violin, reportedly worth ?2.3m (Dh11.6m).
"Waltzes were not meant to be conducted," he said recently in an interview with The Daily Telegraph. "I lead with my bow, my head, my whole body, just as Johann Strauss did." The UK is, it seems, not the only country to have fallen under his spell. In Billboard magazine's list of the top 25 tours last summer, Rieu was in fourth place, ahead of Coldplay, Bruce Springsteen and Celine Dion. Only Madonna, Britney Spears and Tina Turner lay ahead of him.
Having originated in Vienna in the mid-18th century, the waltz, which is traditionally performed in 3/4 time, quickly spread across Europe. It was, though, not without its detractors, many of whom saw the dancers' proximity as "indecent". The death knell sounded when the style began to shift from the ballroom to the music hall. And it was not until Rieu started bringing it to the masses once more, that the waltz experienced renewed popularity.
"My father was a conductor, and I grew up listening to his concerts," Rieu told The Daily Telegraph, "and I noticed that, when he played waltzes as encores, the audience seemed different. They smiled, they started to move in their seats. This music still had a magic power to move people. That made a big impression on me." The recent album sales have, said Rieu's spokesman, partly been due to the proliferation of dance shows like Strictly Come Dancing and So You Think You Can Dance? "The waltz has been an important part of many of these shows and it really seems to have captured the public's imagination," he said. One suspects that Rieu's silver-fox appeal also has something to do with it.
And so what of the album? It has most of the greats, from The Blue Danube and the Boléro to the Radeztky March. They are exuberant and full of colour and it is easy to see why the waltz is going strong 250 years on. Rieu is obviously there, but not to the extent that you would suspect from classical music's poster boy. Having trained at the Conservatoire Royal in Liège and in the Conservatorium Maastricht, he is a gifted player. And he has a few words for those who dismiss his style as populist. "I give myself what I want," he said recently to The Times, "not what people want. I play that music in a way I want to play. I don't change the music: I play it as it should be played. And I take my job seriously."