Image copyright WPA Pool Image caption Pupils at top private schools "give back to society and the economy throughout their lives", Mr Harman will say

Private schools are being used as "lazy shorthand for the social ills of our country", a leading head has claimed.

"It is time to stop scapegoating and start celebrating our schools," Richard Harman told the Headmasters' and Headmistresses' Conference.

Private schools are part of the solution to poor social mobility, said Mr Harman.

But the Social Mobility and Child Poverty Commission said a small elite still dominates top jobs in the UK.

"It is welcome that the private school sector wants to build more partnerships with state schools.

"Breaking down the Berlin Wall between private and state schools is one way of making Britain a socially mobile country. We are a long way from that today, especially at the top of society", commented commission chairman Alan Milburn.

Mr Harman, headmaster of Uppingham School, Rutland, and chairman of the HMC, listed the achievements of independent schools and rejected attempts to "hector", "lecture" and "control" them.

'Social engineering'

"We are not a laboratory for social engineering," Mr Harman said.

"When it comes to social mobility we are part of the solution, not the root of the problem."

More than one in three pupils at HMC schools "are on some form of financial assistance" and between them HMC schools spend £365m a year on fee assistance schemes, he said.

"We want and intend to do more and the impact will be huge if this attitude is reciprocated by government and its unelected officials. We live in hope," Mr Harman said.

Mr Harman said Britain should take "collective pride" that it has "created some of the very best schools in the world."

They are a crucial academic resource, he said, sending pupils to the best universities who will "give back to society and the economy throughout their working lives."

In his speech, Mr Harman attacked the head of Ofsted, Sir Michael Wilshaw and a recent report from the Social Mobility and Child Poverty Commission which said top jobs in the UK are disproportionately held by people educated at private schools.

He said Sir Michael "surely exceeded his brief by demanding that independent schools each sponsor an academy."

"I don't take well to being hectored and I doubt you do either."

Mr Harman also rejected a suggestion by the former education secretary Michael Gove that Ofsted should extend its remit to regulate private as well as state schools.

His speech urged policy makers to draw on the HMC's "centuries of expertise."

"But too often those in power are embarrassed to be seen talking with us, preferring instead to threaten us with loss of charitable status or more state control."

Image caption The HMC has been 'a lone voice' scrutinising the work of exams regulator Ofqual, Mr Harman claimed

The HMC is an "advocate for pupils across the country in all kinds of schools on a wide variety of issues", said Mr Harman.

The association is "a lone voice" scrutinising the work of the exams regulator Ofqual, he claimed.

The speech urged Ofqual to do more to ensure "a high confidence, high trust exams system", providing "air traffic control, not air crash investigation."

"We are speaking up on behalf of fairness for candidates and schools, all candidates in all schools."

Mr Milburn said he agreed the best people need to be in top jobs: "There are many good people who come from private schools."

He added: "It the degree of domination that is the concern...

"The more private schools are willing to work with state schools, the better the chances are of changing that."