The principal of one of Wales’s most famed independent schools says she will resist advice to focus less on the three Rs.

Howell’s School in Cardiff, once attended by singer and presenter Charlotte Church, was visited by inspectors last November for the first time in its 149-year history.

The selective school, which admits girls from nursery to A-level and boys in the mixed sixth form, received a glowing report. It scored seven grade 1s - the first independent school to do so since Estyn took over inspecting private schools in 2004. There was only one drawback: too great a focus on reading, writing and arithmetic in the junior school, said inspectors, who believe it was at the expense of other subjects.

Sally Davis, the principal, welcomed the praise, but said she would be sticking to the traditional curriculum, albeit with a modern twist. “We have been overwhelmed with support from parents who feel we have the balance right,” she said. “If you can’t write or read, you can’t do all the other subjects.”

Mrs Davis said the school would be looking at making literacy and numeracy more theme-based, but without cutting down on teaching time. “We don’t have many formal lessons,” she said. “What we cover is traditional, but we are very creative about how we do it. It all comes down to good teaching and good preparation and planning.”

Inspectors said pupils were taught to question and think deeply about their work. They singled out the excellent relationship between pupils and staff, but also the good resources at the school.

“I admit we are blessed financially, but the commitment of the staff and the way we all work together is the reason we do so well,” Mrs Davis said.

Academically, Howell’s outshines most Welsh schools, including many other private schools.

More than 95 per cent of its girls achieve five or more top-grade GCSEs, and more than two-thirds of passes are A or A*.

Mrs Davis attributes this to single-sex education, which she deems “essential” between 11 and 16. “Girls are able to concentrate purely on academic studies, and they learn in different ways to boys,” she said.

Estyn praised the sixth form for ensuring boys and girls achieved equally well. Nearly all gain two or more A-C grades at A-level.