This man is the hottest conductor in the world. The critics love him. So why aren't Prom-goers snapping up seats to see him?

Tonight the Berlin Philharmonic plays at the Proms. The performance has been sold out for months. Next week the hottest young conductor in the world, the charismatic Valery Gergiev, brings the Rotterdam Philharmonic to the Proms. It has attracted a larger number of critics than any other concert, but tickets are still available.

The public still associates the orchestras of Berlin, New York and Chicago (all of which sold out instantly) with the Olympian heights of classical music. The city of Rotterdam does not cause the spine to tingle in the same way.

Classical music concert-goers, it seems, are as susceptible to the lure of a "brand name" as their counterparts at rock concerts who blithely ignore key personnel changes among the musicians.

Certainly, the aforementioned orchestras are still among the best in the world, but the world of classical music has changed since Von Karajan in Berlin, Solti in Chicago and Boulez in New York ruled relatively unchallenged. As CD buyers know, the less glamorous names on the less glamorous labels at budget prices can produce music which achieves critical acclaim. And the great orchestras can have their off days.

The music critic Norman Lebrecht - whose new book When The Music Stops claims that the big orchestral names "are often overpaid and overplayed" - said yesterday that audiences take a gamble when they buy tickets for the big names.

"There is a premier league of orchestras who, when they play on top form, are unbeatable. But when they play on less than top form they can pull a real stinker. They may have been touring too much or they don't care because money has become more important than institutional pride.

"None of the London orchestras can play as brilliantly as the Berlin Philharmonic on top form; but equally none of the London orchestras can play as badly as the Berlin Philharmonic can do if they don't like the conductor or the coffee wasn't quite right at breakfast."

There is also, says Lebrecht, the problem of too much playing. "You always have to ask whether the orchestra is coming in as a first step on the tour or the third or fourth step. Are we getting wide-awake performances? The New York Philharmonic came in fourth step on their tour. So all these things have to be taken into account. It is a gamble for audiences, though less of a gamble at the Proms when the exuberance and the foot stamping tends to rouse even the biggest orchestras and give them back their old enthusiasm."

But for Lebrecht and other experts there is as much excitement in names that are unknown to the public at large. "The Chamber Orchestra of Europe is one of the most interesting bands around," he said. "Conductors who have worked with them tell me it is a total experience. You're playing with some of the best young musicians in Europe."

At this year's Proms, the premier league names all sold out; but there have been some new British entrants into the top division. Britain's Sir Simon Rattle and the City of Birmingham Symphony Orchestra are also among the hottest tickets. There were sell-outs too for soloist horn player Barry Tuckwell's farewell performance and for conductor Trevor Pinnock with the English Concert Orchestra.

Tickets were also at a premium for the National Youth Orchestra. Are they now a major force among world orchestras? "Possibly," said a Proms official, "but you also have to remember there are a lot of parents and friends."