Arriving at a concert to discover there is no programme and that the audience will be responsible for choosing the setlist would normally trigger a flurry of demands for refunds.

But that is exactly what the maverick Jewish-Hungarian conductor Iván Fischer will bring to this year’s Proms.

Fischer, who prides himself on his capacity to rip up the rulebook, will bring his Budapest Festival Orchestra (BFO) to London next month, with the ensemble promising to play any of the 200-plus pieces up for selection by concertgoers.

3 Iván Fischer, @Marco Borggreve

Iván Fischer (Photo: Marco Borggreve)

“There is a feeling of festivity and uniqueness,” says Fischer, 72, gleefully. “The danger of normal concerts is that they become predictable. And if art or music is too predictable, then it becomes a ritual which doesn’t have excitement.”

The Proms, he adds, are the ideal destination for such an unpredictable concert.

“Because of the atmosphere, the enthusiasm, the audience’s curiosity for new things,” he says. “They are always exciting and always enthusiastic. And this is the nature of music. It’s everything that I stand for.”

Fischer was born in Budapest into a Jewish family 18 years after Hitler came to power, when Hungary was gripped by the antisemitism that saw 500,000 of a population of 800,000 Jews murdered — including his maternal grandparents, at Auschwitz and Buchenwald. His mother, an only child, survived by hiding.

While his parents were not religious, they were Jewish-minded and always had a “humorous” way of looking at things.

9 Iván Fischer, ©Ákos Stiller

Iván Fischer (Photo: Ákos Stiller)

Fischer has long pushed musical boundaries. He founded the BFO in 1983 to blur age-old borders between musicians and the directorial conductor, and the ensemble is renowned for staging innovative concerts, from playing at midnight surrounded by a crowd of young fans lounging on beanbags to breaking into song unexpectedly.

Recently, the maestro even rewrote the tune of one of the world’s best-known compositions — “Happy Birthday” — because, he said, he was fed up with its “very poor melody”.

He believes that his unconventional approach to music likely emerged out of his family’s love of culture, which they treated almost like a religion, and the Jewish trait of questioning: “[Our] gods were Mozart and Beethoven… culture was extremely important in our family and there was a very Jewish tradition of questioning, reinventing, discussing, not taking things for granted.”

While the BFO is performing two other, more traditional, shows at the Proms, the concert without a programme — titled Audience Choice — encapsulates Fischer’s rebellious streak, although the conductor prefers to see himself as a “reformer”.

He is determined to relax the habits surrounding, and perhaps constraining, classical concerts that in his opnion keep orchestras stuck in the 19th century.

“This is precisely when orchestral habits got frozen,” he says.

7 Budapest Festival Orchestra, ©Ákos Stiller

The Budapest Festival Orchestra (Photo: Ákos Stiller)

“Everything is frozen: how many musicians in an orchestra, how the seating is, the conductor-musician relationship. The repertoire [has remained] basically unchanged for the last 150 years.

"An orchestra should open up and serve the community in more styles and forms. They have been put on ice.”

The very role of the conductor too is a “completely archaic idea” , he insists.
Despite his non-religious background, Judaism is part of Fischer’s make up.

In 2014, the conductor and his orchestra toured Hungarian villages, including his own, where Jewish people were annihilated, and he has done what he can to help keep the language of his forebears alive by composing songs in Yiddish: “During the Holocaust, not only were people killed, but a language was also killed,” he says.

“[Many of] those people taken to concentration camps were Yiddish-speaking, and now nobody speaks it. That makes me sad, and when I compose a Yiddish song I feel better.”

It is clear that putting on concerts like his unorthodox Proms show also makes him happy. “I’m not interested in career or glamour,” he says.

“I experience it as a burden. But what I do need is the joy music gives me, and
I love to share it.

“When I see people smile and their eyes light up, that gives me pleasure.”

10 Iván Fischer, ©Ákos Stiller

Iván Fischer (Photo: Ákos Stiller)

Understandably, some of the orchestra’s members are nervous about playing an unrehearsed piece on the spot at the world’s biggest classical music festival.

“But most of them laugh about it,” says Fischer, pointing out that mistakes will be par for the course.

The purpose is not to pull off a “polished, perfect performance”, but to play the music the audience chooses.

“And,” he promises, “it’s a lot of fun.”

Prom 38: Audience Choice is on August 13 at 2pm. The Proms start on July 14.