His critics had been demanding a Clause Four moment - a big symbolic gesture to show the British public that the Labour Party has changed fundamentally. They have it now. Ed Miliband's decision to go into battle against Rupert Murdoch and his minions has helped transform the political and media landscape and renewed his parliamentary colleagues' flagging faith in his ability to lead.

At a shadow cabinet meeting on 12 July, Labour frontbenchers praised his bold interventions in the debate over phone-hacking. Only a week earlier, some shadow ministers had been wary that their leader was planning to set out on such a belligerent and provocative path. Yet ever since the parents of Milly Dowler discovered on 4 July that the News of the World had hacked into the voicemail of their murdered daughter, Miliband has been ahead of the curve: demanding the resignation of the News International chief executive, Rebekah Brooks; calling for a judge-led inquiry into the misbehaviour of the press, police and political class; coming out against News Corporation's take­over of BSkyB.

The previous week, he was being mocked by everyone (including me) for a robot-like television interview on the public-sector strikes, in which he gave a series of near-identical answers to five different questions. Harold Wilson's well-used line has seldom been more apt: a week is indeed a long time in politics.

As he approaches his first anniversary as Labour leader, Miliband has found his voice, adenoids and all, and is speaking for the people, channelling their anger. In the words of the Labour blogger Mark Ferguson, reviewing Prime Minister's Questions on 6 July, Ed spoke for the readers of the News of the World, David Cameron for its owners.

Murdoch headlock

Miliband's critics have gone to ground. Since 4 July, the Labour leader has got the better of Cameron at PMQs, performed coolly and confidently in broadcast interviews and made all the running on the appropriate political response to what is fast becoming the biggest crisis of confidence in the British establishment in living memory.

For a Labour leader to break free from Murdoch's headlock is a historic achievement. Tony Blair described his "grudging respect and even liking" for the media mogul in his memoir, and Gordon Brown - despite winning plaudits in recent days for his condemnation of New International's "disgusting" practices - is said to have crafted his tax policies to appeal to the Murdoch-owned press.

This is about more than hacking. It is about reclaiming the centre ground from the right, around critical issues such as financial and media reform. "I am absolutely a leader placing my party firmly in the centre ground," Miliband told the BBC's Andrew Marr on 10 July, "but there's a new centre ground in our politics."

His allies agree. "The centre ground isn't what Rupert Murdoch or David Cameron says it is," a shadow cabinet minister tells me. "It's what the British public says it is." The crisis in the Murdoch media empire has emboldened Miliband in his mission to rewrite the political agenda. "It's what he has always been about," says a close adviser. "It's what his leadership campaign was centred on."

A friend of Miliband's from his Harvard days in the early 2000s, the academic Archon Fung, remembers how frustrated he was by the failure of the centre left to set the political agenda. "The phrase that resonated from Ed is that the Republicans are 'preference-transforming' and the Democrats are 'preference-adapting'," Fung recalled when I spoke to him earlier this year. "So the Democrats are tacking to where they think public opinion lies, while the Republicans are happy to change opinion, on principle, as Margaret Thatcher did in the UK and Ronald Reagan did in the US."

Miliband, Fung said, believes that progressives should learn from conservatives to lead opinion rather than follow it. "What I walked away thinking is that Ed has a sense of leadership, of making a set of arguments and trying to swing people over to what he views as right and principled, even if they don't happen to feel that way when they're eating their breakfast cereal at eight o' clock that morning."

Miliband's BBC1 interview with Marr on 10 July was the first time since becoming leader that he had been so explicit about his refreshingly Thatcheresque ambitions. However, it also served as a reminder - courtesy of Marr's questions - of his own contentious decision to hire an ex-News International employee, Tom Baldwin, to oversee strategy.

Bold defence

The Tory donor Michael Ashcroft has accused Baldwin of paying a private investigator to "blag" his bank details when Baldwin was a reporter on the Times. He denies doing so, but has Miliband taken an unnecessary risk in hiring him? It was Alastair Campbell, Blair's former press chief, who introduced Baldwin to Miliband. (Baldwin, who has undoubtedly sharpened up Miliband's press operation, seems to see himself as the new Campbell - the posture, the grimace, the potty mouth.) When the Times journalist first went to discuss the job with Miliband at his office in December, the Labour leader remarked: "I spent 15 years trying to avoid having lunch with you."

Nowadays, however, Miliband is ready to defend his director of strategy, as he showed in the Marr interview.

Marr But [Baldwin] used somebody to go into Michael Ashcroft's bank account.
Miliband That's untrue, Andrew.
Marr Are you sure about that?
Miliband That is untrue. Yes, it is untrue.

Given this uncritical endorsement of Baldwin, Miliband had better hope the claims are untrue. He has put his own judgement and credibility on the line. "It is a real worry for us," concedes a shadow minister. Another tells me he groaned as he watched his leader's strident defence - and hopes it won't come back to haunt him.

Despite Cameron's gibe over Baldwin at Prime Minister's Questions on 13 July, Miliband is still in the ascendancy. Friends say he feels enlivened and impassioned. A few weeks ago, James Macintyre and I published the first biography of him. The subtitle includes the phrase "the making of a Labour leader". That is what we have been witnessing in the past few weeks.

Mehdi Hasan is senior editor (politics) of the NS