Alun Jones, president of the Girls’ Schools Association (GSA), said there were “pockets of excellent practice” in state schools but thought that these were rare.
Mr Jones, who is principal of St Gabriel’s School in Newbury, Berkshire, was speaking at the GSA’s national conference in Newport last month.
His comments came as the debate over arts education continues in the state sector.
In July this year, education secretary Nicky Morgan hit back at claims that the government is devaluing arts education, not least via its 90 per cent EBacc policy, declaring that arts education is “the birthright of every child, regardless of background”.
During his keynote speech Mr Jones insisted that the creative arts offer “levels of enrichment” and deliver life-skills that enable students “to reach further in life and career”.
He added: “I believe that the creative arts must have equal parity with STEM subjects as a vital component of academic and life success and mental wellbeing.
“In a society where self-direction, the skills to manage your own learning and the ability to persevere – without that constant need for instant gratification – are becoming more important than traditional achievements, we ignore the creative and expressive arts at our peril.”
Mr Jones also demanded a better, more effective system of regulation for all schools.
He said: “The amount of regulation that schools are subject to has grown exponentially and is coming at schools faster and ever more frequently.
“Of course I completely agree that we must have robust legislation that keeps children safe and gives everyone clear guidance about how to do that. But the sheer volume of regulatory change – plus revision upon revision, sometimes only weeks later – is untenable for both independent and state sector schools alike.
“The impact on workloads has been massive and the increased stress among staff is worrying. Schools are trying to implement new regulations at the very point in the school year when they should be focused on teaching.”