Andrew Grant, who took over as chairman last week, said the Department for Children, Schools and Families recently contacted independent school leaders in alarm after media reports of an exodus from fee-paying schools because of the recession.
"It's quite difficult in those circumstances to maintain that the independent sector is not providing considerable public benefit," Mr Grant told The TES.
"Parents who send their children to independent schools have already paid for education through taxes. So it seems perfectly moral and logical that, if you choose to spend your own money on independent educaton, it should be allowable against tax."
Mr Grant, 56, a father of two, was grammar school educated and the first member of his family to go to university. He is, unsurprisingly, a keen advocate of selective schooling.
Nonetheless, he is sceptical about the Charity Commission's stipulation that independent schools can only retain charitable status if they offer assisted places.
"This ignores the extent of relief to the public purse from parents who have already paid for state education," he said. "Or the extent to which the independent sector sustains university departments in certain subjects: the sciences, modern languages, classics."
The Headmasters' and Headmistresses' Conference represents 250 independent schools. The latest census of the sector, released last week, showed that a third of pupils in these schools receive part or full bursaries. But schools may struggle to continue subsidising these places.
"Education isn't immune from the economic climate," said Mr Grant. "But you can defer changing your car. You can't defer important stages in your child's education.
"We know there's going to have to be some belt-tightening. Yes, increasing class sizes is a possibility. Reducing the number of subject options might be another.
"But HMC schools are at the quality end of the market," he points out. This quality, he believes, is sustained by capitalising on the freedom that independence brings. At St Albans, he has already replaced the "stultifying" English literature GCSE paper with the International GCSE.
"I predict increasing interest in the IGCSE in our schools," he said. "I predict no diminution in the interest in the International Baccalaureate, and increasing interest in the pre-U."
Separate exams may, of course, create even greater divisions between sectors. But Mr Grant is sanguine: "Yes, that divide will expand. But there's a very simple solution: make the qualifications that we feel are best suited to our pupils available to all pupils.
"We should be making better use of independent schools. These are among the best in the world. It takes real perversity to want to marginalise them."
Andrew Grant - CV
- 1971: Open Exhibition to read English at Corpus Christi College, Cambridge
- 1976: English teacher, Merchant Taylors' School, Middlesex
- 1983: Head of English and drama, Whitgift School, Croydon
- 1990: Second Master at Royal Grammar School, Guildford
- 1993: Head, St Albans School, Herts
- 2009: Chairman, Headmasters' and Headmistresses' Conference.