A former Conservative Prime Minister has attacked the “truly shocking” privilege of the privately educated elite.

Sir John Major, who went to a comprehensive in south London and left school with three O-Levels, said that the “affluent middle class” dominated “every single sphere of British influence”.

He said “hard graft” was not enough in today's society for state school educated pupils to reach the “upper echelons of power”.

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In his speech to the South Norfolk Conservative Association’s annual dinner on Friday evening, reported by the Daily Telegraph tonight, Sir John said: “I remember enough of my past to be outraged on behalf of the people abandoned when social mobility is lost.

“Our education system should help children out of the circumstances in which they were born, not lock them into the circumstances in which they were born.

“We need them to fly as high as their luck, their ability and their sheer hard graft can actually take them. And it isn’t going to happen magically."

He added: “In every single sphere of British influence, the upper echelons of power in 2013 are held overwhelmingly by the privately educated or the affluent middle class. To me from my background, I find that truly shocking.”

Sir John said members were right to feel “unsettled” by “bewildering” changes such as the Coalition’s decision to legalise same-sex marriage.

He said: “Social mores have moved on from the way in which we were brought up, with the values that we had. They have moved and changed. And that is why issues such as gay marriage have proved so toxic for the Conservative party. Because for many Conservatives, people who are conservative because their instinct is to conserve, to change slowly.

“We may be unsettled by them, but David Cameron and his colleagues have no choice but to deal with this new world."

Sir John, Prime Minister from 1990 to 1997, said: “If members of our party wish to criticise the Government that it is fine. It is their right and it is often productive to do so. Can we win this election? I am sure that we can but only if we pull together.”

Richard Bacon MP, who hosted the dinner, told the Telegraph: “It was a superb speech which drew attention to the huge damage done to social mobility especially by the last Labour Government.

“I think the Coalition is acutely aware of this problem and is taking steps to address it such as cutting tax for the low paid and the pupil premium but it is an enormous task.”