But in a scathing attack on the PM, Michael James, chairman of the Society of Headmasters and Headmistresses of Independent Schools, accused Tony Blair of manipulating the education system to get his own children into good schools.
Harriet Harman, the Solicitor General and south London MP, who snubbed her local comprehensives to send her son to St Olave's, a grammar school in Orpington, Kent, also came in for severe criticism.
"This issue is often portrayed as some kind of latterday class war," Mr James told his society's conference in Southampton. "I find it quite repulsive to listen to public school toffs like Tony Blair and Harriet Harman speaking about educational opportunity when they have blatantly manipulated the system.
"Some of us here come from genuinely working-class backgrounds. We are people for whom education really was a life-changing experience.
"We were lucky - because we were of high academic aptitude and the mechanism then existed to give us social mobility. Under the present system, no child in the road where I grew up can have the same chance."
Mr James is the 58-year-old headteacher of Rydal Penrhos school, in Colwyn Bay, north Wales. He is the son of an electrician and grew up in a semi-detached council house in Newcastle under Lyme, Staffordshire.
Mr James passed his 11-plus, and was therefore able to go on to Newcastle under Lyme school - at that time a grammar - and later went on to read geography at Oxford university. His brother Peter, 56, went to a secondary modern and now manages a steel fabrication business.
Mr Blair, who was educated at the private Fettes college in Edinburgh, where fees are pound;13,287 (day) and pound;19,329 (boarding) per pupil per year, rejected comprehensives in his local area of Islington, north London, to send his sons to the Roman Catholic London Oratory school in Fulham, south-west London. His daughter travels to a Catholic girls' school in Hammersmith, west London.
Mr James, who has taught in state and private schools, backed remarks by Anthony Seldon, head of Brighton college, about the "moral unworthies" who move house in order to be in better school catchment areas.
He urged the Government to give the poorest parents vouchers to pay for private-school fees.
Fees at Rydal Penrhos range from pound;10,000 (day) to pound;16,500 (boarders) per pupil per year and the school spends 16 per cent of its income on scholarships and bursaries including money it receives from the Government for assisted places. This will be substantially reduced next year when the last assisted places are phased out.
The Southampton conference was the furthest Mr James had had to travel for one of the society's events. "I am not an effete southerner, and this is a long way south of the black pudding belt for me," he said.