Not many acclaimed pianists get stopped by the police minutes before a televised performance but it happened to Brad Kella. On his way to audition for TV talent show The Piano at Liverpool Lime Street station, the self-proclaimed “little scally” was approached by an officer.

“I was stood by the station entrance, looking really nervous,” Kella says. “This policeman came over and asked what I was up to. I think he was expecting me to pull something out of my pocket. I said I was about to play piano for Claudia Winkleman. His face completely changed.”

The 22-year-old was unfazed (“It often happens because I look like a stereotypical lad”), sat at the station’s street piano and brought the busy concourse to a standstill. As a large crowd gathered, many were moved to tears by the beauty of his music and potency of his story.

Kella opened up about his chaotic childhood before performing his original song New Beginning – dedicated to the foster parents who took in him and his twin brother, Aron, when they were aged seven. “Growing up, we had no routine,” he said. “I never went to school. I’d roam the streets all day until about 11pm, causing mayhem.”

He credits his foster parents, Frank and Evelyn (whom he fondly calls “Ev”), for turning his life around. “When I got put in foster care, I was confused and scared. I clung to the railings outside their house, refusing to go in. But they gave us routine, regular bedtimes, took us to school. They gave us everything and more.” Kella was supposed to be there for one night. He ended up staying for 12 years.

With help from a music fund for children in the care system and Ev chipping in the difference, they bought his first Yamaha keyboard when he was 14. From that moment, he says, “my life changed”. He can’t read music and is entirely self-taught. “I don’t know if it’s a God-given gift, but I get literally lost in music. I could express my emotions through the piano, which helped massively with my mental health. The piano saved my life.”

He entered the hit Channel 4 competition to encourage other children in care. “I want to make my family proud, my city proud, and hopefully inspire people in similar situations. Frank and Ev gave me belief. It goes to show that if a kid is nurtured and loved, they’ll be fine. Kids have tough starts but it’s not their fault. We’re normal people, capable people, just searching for a new beginning.”

Teenage prodigy Lucy Illingworth, who is blind and autistic, was the headline act of the ivory-tinkling contest’s debut series. Kella has become the breakout star of its second run. His audition has already amassed 1.5m views across social media platforms.

“It was the sort of magic you can’t predict,” says the show’s creator, Richard McKerrow. “Brad was unorthodox and untrained but love poured out of the piano. He’s from the other side of the tracks but train stations are egalitarian. It was like a community came together. I remember my colleague in the gallery going: ‘This is the most powerful moment we’ve had.’”

Kella was one of seven gifted amateurs out of 75 hopefuls, put through to The Piano’s concert finale, which airs on Sunday. “I’ve never met a pianist who writes and plays with such sensitivity,” says the pop star Mika, one of the show’s judges. “Brad’s story is a brilliant example of the power of the piano to change your future.” Kella’s mentoring masterclass with Mika’s fellow judge, classical maestro Lang Lang, was his first ever lesson: “Not a bad first teacher, right? I grew up watching him on YouTube. It’s absolutely mad.”

On-stage at Aviva Studios, in Manchester, Kella will play another original composition, written specially for the occasion, called Frank & Ev. His foster parents will be watching from the sellout crowd, unaware that he has named the piece in their honour. No spoilers, but there isn’t a dry eye in the house. “It’s all happy emotion,” he says. “The piece is a huge thank you for the person they turned me into.” He even smartened up for the big night. “I went from a tracksuit to a black suit,” he grins.

He’s at pains to point out that this isn’t a sob story. “The best thing about my story is it’s not finished yet. I hope to be a voice for us care kids and show what’s possible. I’ve had everything against me. You’re treated as a number. People look at you differently. We need to get more instruments to kids in care. It’s such a struggle, so mentally draining, but music is healing.”

His ambition is to compose film soundtracks. “Brad blew us away,” says Winkleman. “He sat at the piano and we were transported. I just know he’s going to be a film composer. Mika and Lang Lang know it too.”

Kella and his girlfriend, Abby, are now parents themselves. Their three-year-old daughter, Phoebe, will be joined by a baby sister, due in a few weeks. “If she comes early and is born this Sunday, we made a bet that I’m allowed to call her Melody.”

Source: theguardian.com