Many years ago, Rupert Murdoch was not an Establishment figure.

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The Establishment was the Conservative Party, the House of Lords, the Church of England, the civil service, the top military brass, prominent industrialists and heads of the nationalised industries. It was not necessary to be a millionaire to belong, but it was almost obligatory to conform to the social rules learned at the best public schools.

But after Rupert Murdoch had been allowed to buy the News of the World from Sir William Carr, in 1969 – because an Australian was judged preferable to the rival bidder, Robert Maxwell, a Czech Jew – the Establishment found it had given house room to someone who did not conform. He did not hanker after an invitation to Buckingham Palace or a seat in the House, nor even British citizenship. The News of the World's new boss let the establishment know what he thought of its sensibilities by buying the memoirs of the prostitute Christine Keeler, who had been at the centre of the Profumo affair. The Establishment saw Jack Profumo as one of its own and thought it wrong he should be humiliated by the revival of a six-year-old scandal. The reason Murdoch was allowed to buy The Sun was that it was a loss- making paper overshadowed by the more robust Daily Mirror. No one foresaw how Murdoch would turn an ailing tabloid into Britain's best selling daily, and a source of ready cash for further expansion.

Then came the rise of Margaret Thatcher, herself something of an outsider. After Murdoch had used his newspapers to help her to victory, she rewarded him by allowing him to buy The Times and Sunday Times, and backed him as he smashed the print unions. It was the start of a 30-year reign during which Rupert Murdoch enjoyed the reputation of a modern Warwick the Kingmaker. No political party has won a general election from 1979 onwards without the backing of the Murdoch press. After the Tories' unexpected victory in 1992, The Sun crowed: "It was The Sun wot won it."

That may not actually be true. It is possible that instead of creating the winners, what Murdoch did was shrewdly back whoever was going to win anyway. But the point was that politicians from Tony Blair to David Cameron believed Murdoch had the power to make or break them.

This gave the Australian/American mogul a power no one in the old Establishment had ever wielded. He could summon prime ministers to hear his views on matters of state or to add prestige to his guest list on social occasions, such as the nuptials of his court favourite Rebekah Brooks.

Lance Price, who worked in Downing Street during the Tony Blair years, has written that Murdoch "seemed like the 24th member of the cabinet. His voice was rarely heard ... but his presence was always felt." There is no doubt his influence was equally great during the first year of David Cameron's government.

Out of this limitless influence came the hubris. A few acolytes in a corner of the Murdoch empire apparently thought the law could not touch them, and embarked on a course of action which destroyed the News of the World. Suddenly, political leaders have found the courage to criticise the vast conglomerate which had previously held them in thrall.