The one-armed concert pianist: Nicholas McCarthy on Britain's Got Talent and the Proms

Nicholas McCarthy does not need a Google alert to remind him when another series of Britain's Got Talent is looming – or, depending on your viewpoint – threatening. For the past few years now, the show's producers have contacted him months before the transmission date, asking whether he might like to take part. They are as persuasive as producers of any show that requires talent greater than an overweight man playing the spoons must be, but McCarthy proves resistant.

"I'm well aware that I would have a massive fan base as a result of the show," he says, breezily, "although I don't think I would win. It would boost my profile, certainly, but as what, exactly – just another TV talent show contestant? That doesn't interest me."

He pauses here to take a sip of his water, tap water. We are in a bar in central London, and I had offered him something with bubbles in it, a Perrier perhaps. But he insisted that tap would be fine.

"I'm playing the Purcell Room in London next month," he says of the Southbank venue that frequently plays host to intimate classical recitals. "I wouldn't be able to do that if I was merely another TV talent show wannabe, would I?"

Nicholas McCarthy is a classical pianist, and a great one. There are many classical pianists that do not come to the attention of the mainstream media, however, much less receive invitations to perform before a TV judging panel that includes Amanda Holden. But McCarthy is a classical pianist with a difference: he has just one arm. This makes his achievements all the more remarkable, and inspiring. You watch him on YouTube with a sense of awe while also guiltily acknowledging that his disability almost renders his talent a mere gimmick. And so McCarthy, 25, finds himself in a curious position: a genuinely gifted musician to whom the novelty tag so tenaciously clings.

"Oh, I'm used to it, it's fine, really it is," he says, shrugging. "It's my USP, isn't it? A point of interest. I know lots of pianists, two-handed pianists, that are far better than me, and they get no media attention at all, whereas I do. Never underestimate people's curiosity, I suppose…"

McCarthy was born in Surrey to non-musical parents. They had been anticipating a normal, healthy baby; the lack of half his right arm, then, took them by surprise. It took the doctors by surprise, too. "It never showed up on the scans," McCarthy says. The doctors, scratching their heads, could offer no polysyllabic name for it, or suggest a possible condition. "The arm may have been caught up in an amniotic band," he says now, cradling it at the elbow, where it abruptly ends, "or the umbilical cord. Nobody really knows. It's a mystery."

But McCarthy didn't need a name for it, and simply displayed the kind of resilience only children can. He was the first person in his street, he says, to ride a bicycle unaided with stabilisers, and soon developed a quick sense of humour at school to counter any bullying.

He also had dextrous ambitions: by his early teens, he wanted to become a chef. But then he heard a friend playing classical piano, and something resonated. "It's like I became immediately obsessed," he says.

He listened to Brahms, to Beethoven; his parents, wanting to encourage any potential vocation, no matter how unlikely, bought him a cheap keyboard and were soon mistaking the sound of his playing for the radio blaring out Classic FM.

Piano lessons followed, and he quickly outgrew successive teachers. He was referred to a specialist piano school in Croydon, but the headteacher there was sceptical. She told him that he would be of little use with only one hand. How could he even play the scales?

"I told her I didn't want to play the scales; I wanted to play music," McCarthy says. "She hung up on me. I was 15 at the time, and devastated."

Shortly after, he successfully auditioned for a place at the Junior Guildhall, and was later accepted at the Royal College of Music, the first one-armed pianist in its 130-year history.

Much of his repertoire has been adapted, either by him or by others, for the left hand alone, but there is already a vast repertoire written specifically for the left hand. "I'm spoiled for choice," he says, and tells me the story of Paul Wittgenstein, an Austrian pianist who lost his right hand during the First World War and whose wealthy family subsequently paid some of the most famous composers of the 20th century – Ravel, Prokofiev, Benjamin Britten – to write pieces exclusively for someone with his limitations.

McCarthy nevertheless remains in a distinct minority, and so it's little wonder that his story was quick to garner publicity. Three years ago, while still at the Royal College, he was interviewed for daytime TV. This brought him a burgeoning fanbase for whom he recorded two self-funded albums, the most recent of which came out late last year. Daytime TV exposure is all very well, he says, but he wants more than that; he wants to be taken seriously, and accepted by his peers.

This is no small feat for any budding classical musician, with the classical world often regarded as aloof and exclusive, its default position regarding potential newcomers one of immediate suspicion. But Claire Jackson, editor of International Piano magazine, tells me that McCarthy's talent shines.

"Left-handed piano music is often incredibly difficult to play," she explains, adding that, historically, two-handed pianists would often play with just the one hand for no other reason than to show off. "But what Nicholas does is far more complex, and so on a completely different level."

She says that it would be easy for him to cash in, to go the crossover classical pop star route like Myleene Klass and Katherine Jenkins. "He could have done it and made a lot of money, but Nicholas genuinely wants to be playing at the Proms, he wants to be highly regarded."

And will he be? "He's certainly good enough," Jackson says.

Back in the bar, McCarthy is lamenting the fact that he didn't come of age in the 1930s. "That was when classical music was mainstream, and everybody had a lot of respect for it," he says. "That's why I love it when I get fans who perhaps haven't been to classical concerts before, and who go away converted. Yes, they like the familiar pieces, the pieces they've heard on adverts, but they also like the more obscure stuff. They realise that classical music is amazing, and that to watch it is something quite special, regardless of how many hands you play it with."

Nicholas McCarthy plays London's Purcell Room on 9 March. A new album follows later in the year