Mary Ann Sieghart: Power has shifted back to the people

Politicians will be more worried about incurring the wrath of voters than the wrath of a proprietor of a discredited company

To crush a bully, the calculus of fear must be transformed. Each potential victim – terrified of being picked on – has to trust that everyone else will put aside their fear and join him in defying the aggressor. Eventually, if all the victims stand together and refuse to be cowed, the bully has to slink away.

Until now, few MPs have dared individually to stand up to News International for fear that they would be done over by the News of the World. This was no idle threat; it happened, for instance, to the Labour MP Chris Bryant. Few journalists have dared to do so for the same reason – with the added worry that they would never in future be able to work for any of the four papers that make up 37 per cent of Britain's newspaper circulation.

For party leaders, the calculus was even starker. Nick Clegg, to his credit, has never sucked up to Rupert Murdoch, but then there was never any danger of a News International paper endorsing the Liberal Democrats in the first place. Labour and Conservative leaders have always known that if they turned against the most powerful man in the country, their parties would be trashed in the pages of nearly half Britain's newspapers – to the advantage of the other main party.

So defeating the bully could work only if both party leaders were determined not to flinch. I am not suggesting that Ed Miliband and David Cameron colluded with each other last week. But Miliband calculated, rightly, that public opinion was so strongly behind a challenge that Cameron would not dare to defend Murdoch and News International if the Labour leader attacked them.

MPs sensed the change in the mood too. At the emergency debate on phone hacking on Wednesday, dozens of people spoke who would have remained silent before.

And what had happened to public opinion? Well, at last readers had started to question what went into the stories that they so enjoyed reading. Just as shoppers eventually turned against battery-farmed chicken and clothes made by child labour, so they finally began to take an interest in the methods used to fuel their diet of tittle-tattle. It was about time, as these practices have been widespread for decades and it's been hard to rouse any public anger about them before now. Most readers simply preferred not to know, just as some would rather not know what's in their meat pie.

I've commented before on the callousness readers reserve for people in the public eye, who are deemed to forfeit any human right to privacy as soon as they become successful in their chosen field. It was only when the News of the World, a newspaper that claimed to represent the ordinary person, had – in the cruellest possible way – turned its dark arts on ordinary people that the public fury was ignited. And then it was able to spread, thanks to Twitter and Facebook. Huge companies realised they would suffer reputational damage or boycotts if they advertised in the paper. Members of the public, who used to shrug their shoulders and ask, "Well, what can I do about it?", found they suddenly had power to effect change. And boy did it work.

That I am celebrating the success of people power may sound hypocritical from a journalist who spent 19 years at The Times, at the more salubrious end of the Murdoch empire. But I was always uneasy about the nastiness of what were then known as the tabloids, and I wrote as much at the time. It was never going to do my career at News International any good, and it reaped the inevitable revenge from the Daily Mail. (Once, when I had assailed the Mail for its intrusiveness, a friend there heard the diarist attack dog ask the Managing Editor, "Have you got that file on Mary Ann Sieghart?")

Miliband too has had several threatening conversations with News International executives since he took his stand. But we shall now treat with the necessary scepticism any attack on the Labour leader from a News International paper. Their power to wound is waning.

Now is the time to exploit that weakness. For it is surely wrong that a business that not only indulges in criminal activity, but lies about it and covers it up, should be allowed to expand its already vast media reach. On Wednesday, Labour will introduce a motion in the Commons that would prevent News Corp from buying the whole of BSkyB until criminal investigations are complete. Miliband's office has been taking legal advice and talking to Lib Dems and Tories who have concerns about the takeover in order to draft a motion that will attract the widest cross-party support.

No one has yet seen the exact wording, but as long it doesn't try to score party-political points, the Lib Dems will support it and so will quite a clutch of independent-minded Conservatives. The Tories haven't yet decided whether to whip their MPs, but they might be wise, if Labour's motion is going to win anyway, to leave it to a free vote. For, as a Cabinet minister told me yesterday, "If they let the deal go through now, it will smell to high heaven, and if they do it in three months' time, it will still smell." The opposition of the House of Commons to an immediate deal, while not binding, would be a useful justification for a delay.

The Lib Dems have always been against the concentration of media power that News International represents. The Tories, though, have never cared much – indeed it was John Biffen, during the Thatcher administration, who waved through the purchase of The Times and The Sunday Times, bypassing the Monopolies Commission. So it was quite a surprise to talk to a Conservative MP yesterday and hear him say, "When media power is in too few hands, it has a chilling effect on democracy, as we've seen. Too few people calling the shots is dangerous. There should be a bigger discussion about monopolies in the media."

One intriguing question is whether that discussion will extend to any attempt by News International to replace the News of the World with a Sun on Sunday.

The company will argue that it only represents a return to the status quo. But the status quo – 37 per cent of national newspaper circulation – was already far too high. In any other sector, it would trigger a Competition Commission inquiry, so why not in newspapers, which are particularly sensitive to monopoly abuse?

Murdoch is used to getting his own way. Not just in Britain, but in Australia and America too, he has leaned on politicians to have regulations changed in his favour. In his native Australia, there was even what came to be known as the "Murdoch Amendment" to the broadcasting laws, which allowed him to own a TV licence even though he didn't live in the country.

Well, the calculus of power – as well as fear– has now changed. Politicians will be more worried about incurring the wrath of voters than the wrath of a proprietor of a discredited newspaper company. Murdoch will no longer be able to snap his fingers and have a Prime Minister stand to attention. And Britain is all the better for it.

m.sieghart@independent.co.uk