“Like climbing an infinite stairway, one step at a time.” That is how Pavel Kolesnikov describes working on JS Bach’s Goldberg Variations, one of the outstanding releases of last year. On Friday 10 September, he will perform them at the penultimate night of the Proms. “I’ve never had the chance to dedicate so much quality time to a piece before,” he says when we meet in a tiny cafe in central London. The city has been home since the Siberia-born Kolesnikov, now in his early 30s, came to study at the Royal College of Music. He had grown up listening to recordings of the Goldbergs by Glenn Gould and Rosalyn Tureck, but had never considered performing them himself – “I did not feel I had anything to add”. Then, out of the blue, in autumn 2018, he was contacted by the Belgian choreographer Anne Teresa De Keersmaeker: would he be interested in collaborating on a dance piece? It felt like serendipity. “For several years, I’d been thinking that I’d be interested in working with a dancer.” He was already a fully paid-up admirer of De Keersmaeker’s works based on Bach, especially her version of the Brandenburg Concertos (“I’ve seen that piece five or six times: it’s incredible”). So, in autumn 2018, they began an intense period of work together on the Goldbergs. It was a very different proposition to the Brandenburgs, which involved an ensemble of musicians and dancers; this would be just Kolesnikov and De Keersmaeker on stage together for 85 minutes. First, he worked on his own analysis of the music, variation by variation. “Every few weeks, we would meet in Brussels and have an all-day session, mostly talking about what I’d discovered, maybe playing with ideas. Once you start working on a piece like that, it’s like archaeology.” He made De Keersmaeker a working recording of the whole work, then one of just the basslines. She had most of the choreography ready – and then Covid struck. “When we were allowed to travel again, I took the first train I could to Brussels … out of complete lockdown, I went into rehearsals for 14 hours a day, non-stop, for two weeks. And then we did the premiere.” Amid this, he made his glorious, mischievously eloquent recording for the label Hyperion. Yet this isn’t a soundtrack to the dance work – far from it. “Some solutions are different. I was going for a sound that is completely weightless. When Anne Teresa heard it, she told me she could not dance with it, and I understand why – it doesn’t have a physical aspect at all, it’s happening in your mind. It’s a palace of sound that is being built by your own imagination,” he says. “And now, when I’m performing the piece on my own, it grows independently and I arrive at ideas that are not there when I perform it with Anne Teresa. It’s developing in different directions, growing like a tree, and I like this feeling very much.” The weightlessness of sound that Kolesnikov was aiming for – and achieves so convincingly – on the recording informed his choice of piano: a modern Yamaha, but one strung so as to have a distinctively soft, woody sound. It is almost reminiscent of an instrument from the 19th century, or even earlier. He wasn’t aiming for “authenticity”, though; he is interested in hearing other pianists on historical instruments, but has never been tempted to work with them himself. “For me, one of the ultimate goals of a performance is to make pieces come across as something new, something unexpected and fresh. As soon as you start working with historical instruments, you are jeopardising this aspect. It is very difficult to get away from that; some performers manage it magically, but I don’t see myself doing that.” It is also hard to get away from the mythology that has built up around the Goldbergs, specifically the story recorded by Johann Nikolaus Forkel, Bach’s first biographer, which claims that the Variations were written for one of Bach’s pupils (who gave the works their title) to play for his insomniac employer, a Russian count, in the small hours. Many think Forkel was making things up; for Kolesnikov, that doesn’t necessarily matter. “When we approach a piece like this, it’s unfair to strip it of all those meanings it has acquired over time,” he says. “Some are controversial, some conflict, but everything that happens to the piece belongs to its story. This lends it great flexibility. I’ve never felt uncomfortable playing it anywhere – at home for close friends, in an empty Wigmore Hall, or in the Châtelet in Paris with Anne Teresa, for maybe 1,500 people.” And now, on a flying visit to London in the middle of a Brussels run of the dance piece (he hopes it will come to co-producer Sadler’s Wells next year), he will be playing it at the Royal Albert Hall, to a potential audience of three times that. An archive-hunting friend has suggested to him that it might be the first time in the festival’s history that a solo pianist has had a prime-time, early evening Prom all to themselves. Is he daunted? “Maybe I will be intimidated on the day, but at this point I’m really looking forward to it. I think the piece has the power of organising that space. Bach’s music has endless levels of richness and there’s always something that fits.”