The only part of Pimlico school recognised for its excellence by Ofsted inspectors is in danger of closing due to funding cuts.
Pimlico Special Music, the only state-funded music school in England, has 110 pupils who perform in ensembles and choirs and regularly take part in concerts across England and Europe.
The pupils do all their regular academic study in Pimlico school, but win their place in the music section through auditions when they are in Year 6.
They then get up to three hours of specialist tuition each week in the music school's separate site, two minutes walk from the main school.
Funding for Pimlico Special Music has been cut over the past two years after a change in government guidelines, which say more money should go to widening participation in music at primary schools.
More cuts are expected, which means the centre will have to raise its Pounds 250,000 annual budget from other sources.
"What we have here is outstanding," says Jo Rawstron, the director of Pimlico Special Music. "The pupils are so talented, they constantly amaze me. We are determined to keep it going."
Miss Rawstron is exploring different options including turning the music school into a charitable trust. Greater links with other schools to create a Westminster youth music trust are being considered, as is expanding the school to include art, dance and drama. An external fundraising company has been employed to help boost income.
"We want to create something new and exciting but we need support," says Miss Rawstron.
The school takes both accomplished musicians and children who have not had formal training but show talent.
Successful applicants learn at least two instruments and sing in its choir.
"The music scheme offers access to excellence to children whatever their background," says Ian Welsh, whose son is a pupil. "It would be a tragedy if it were lost."
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