As concern grows over Rupert Murdoch’s £11.7bn bid to buy out Sky, Tom Watson has suggested Labour grandee Gerald Kaufman, who died last week, might have been responsible for turning the media mogul from a youthful left-winger “to the dark side”.

Mr Watson, Labour’s deputy leader, wrote a blog post paying tribute to Mr Kaufman, but said the late politician “may have changed the course of media history” by falling out with the newspaper baron at Oxford University, when both were Labour activists.

The young Murdoch was a self-declared socialist in 1952 when he ran to be secretary of Oxford’s Labour Club using the campaign slogan “Rooting for Rupert.”

He won the election but was prevented from taking office by Mr Kaufman who, as chair of the Labour Club, decided the Australian had broken the rules by canvassing for votes during the election.

Student newspaper Cherwell declared after the election result: “Australian ex-journalist, Rupert Murdoch... bombarded Club members with so many plaintive appeals that undergraduate canvassing and socialist majorities hit new highs.”

Mr Watson, who uncovered the story while researching his book, Dial M for Murdoch, suggests Mr Murdoch’s disillusionment with the “anachronistic” rules of the Labour Club which did not allow for his “impressive” style of campaigning may have turned the Australian away from youthful idealism to relentless entrepreneurship.

Mr Murdoch, whose father was a well-respected journalist and editor, was assistant editor of the Labour Club newspaper, the Oxford Clarion, during his time there.

His father died the same year as the Oxford election fiasco, prompting the student to take control of his father’s company, News Limited, which he rapidly built into an empire by turning his attention to acquisition and expansion, first in Australia and New Zealand and later in the UK and the US.

In a biography of Mr Murdoch written by William Shawcross, the billionaire media mogul angrily recalled the Labour Club election episode.

“F****g Kaufman. He was the same then, a greasy know-all. They found a list I had of people I thought would vote for me… that was the evidence against me. There was a kangaroo court. They said I had clearly been canvassing for votes. I was expelled for breaking the rules. Everyone canvassed for votes.”

According to the biography, Mr Kaufman declined to give his version of events in response to Mr Murdoch’s recollection.

Mr Watson said: “When I spoke to Gerald about it, he shared the whole story. I felt he was a little anguished about the incident, maybe even regretful. He managed to portray contempt and pity for Murdoch in equal measure.”

As owner of newspapers including The Times and The Sun, Murdoch is regarded as having played a key role in the re-election of successive Tory governments in the 1980s and 1990s.

The front page of The Sun famously declared “It’s The Sun wot won it” after John Major saw off the challenge from Labour’s Neil Kinnock in 1992 following its front page warning headline: “If Kinnock wins today, will the last person to leave Britain please turn out the lights?”

Sir Gerald Kaufman: Tom Watson says the late politician ‘may have changed the course of media history’ by falling out with Murdoch at Oxford University (PA)

Mr Mudoch’s media conglomerate, 21st Century Fox, is bidding to formerly take full control of Sky. He and his family own News Corp as well as Fox through the Murdoch Family trust.

Campaign groups – most notably Hacked Off, which sprung up in the wake of the phone hacking scandal – have called for the bid to be referred to Ofcom on the grounds that the Murdoch family are not “fit and proper” people to hold a broadcasting licence.

A statement from Hacked Off said: “We believe that it is unsafe and contrary to the public interest for a major British broadcaster to be wholly owned and run by those with such a shocking record of governance without proper scrutiny.”

Mr Murdoch’s previous bid to take control of Sky – then BSkyB – fell through in the wake of the damning Leveson Inquiry into the phone-hacking scandal, but his empire has returned for a second bite at the cherry.

In 2014, MPs found that Mr Murdoch exhibited “willful blindness” to the goings-on at News Corp, concluding that he was not a fit person to exercise stewardship of a major international company.

A petition on 38 Degrees opposing the takeover bid, which describes it as a “power grab”, has been signed by more than 285,000 people.

It says: “Murdoch already has too much influence over our news. This new power-grab would give him even more. The more power Murdoch has, the more he makes politicians listen to him instead of voters.”