Since last September more than 150 11-year-olds in Year 7 have been given 20-minute lessons once a week in groups of five, learning basic musical theory and keyboard technique.
The scheme, which the school believes may be unique, has been a hit with pupils. More than 20 in Year 11 have opted to study a musical instrument formally - more than double last year's number.
"It has helped me a lot," said 11-year-old Hannah Gould, bravely attempting to demonstrate the pop classic "By the Rivers of Babylon" on her electronic keyboard. Like most of the children in her year group, she had never played keyboards before arriving at Ernulf. "I realised quite quickly that tunes I thought were really complicated are actually quite easy. It encourages you to tackle difficult things."
Recent research has backed the claim that music improves a school's general performance. A study in the United States, aired last week at a conference organised by the School Curriculum and Assessment Authority, found that pupils aged five to seven scored far better in mathematics after being given extra music and art lessons.
Examination results at Ernulf have already improved dramatically over the past three years as part of a drive to raise standards, with the number gaining the top three GCSE grades leaping 20 per cent. The school now has 52.6 per cent of pupils with the top grades, compared to an average in the county of 46 per cent and it hopes to continue improving these scores.
To launch the new policy, Ernulf spent several thousand pounds on new electronic keyboards, which it chose because, with fairly basic fingering, they can produce an attractive backing and drumbeat. Pupils see the keyboards, used by many pop groups, as much trendier than the old-fashioned piano.
The policy is also aimed at making sure all pupils are given the chance to succeed in music. "This is an entitlement curriculum," says deputy headteacher Jenny Knight. "We have some very talented children whose parents can't afford to pay for lessons. This is a way of enabling those children to develop a musical expertise."
The policy is in its early days, and it is too soon to measure any increase in academic performance resulting from the keyboard lessons. But David Rigley, a highly experienced keyboard and brass musician, who teaches the keyboard groups, says: "Music is like a barometer. Parents somehow know that if pupils are doing well in music, they're likely to be doing well in other subjects too. Now the research is proving that intuitive feeling to be true."