It is the 8th of May 2015 and Ed Miliband has won the election. Amid scenes that were simply inconceivable two years ago, the incoming Prime Minister, Justine and the bleary-eyed Miliband children assemble outside Number 10. World leaders phone in their congratulations. Political pundits recount the story of a once-forgotten brother who, for the first three years of the Labour leadership, was written-off as a political non-entity, compared to an automaton and dubbed ‘Red Ed’. No one is laughing now.

It is rare that public opinion shifts with such sharp, sudden and forceful vigour that the country incurs collective whiplash and reassesses its collective wisdom.

The last abiding memory of this was the phone hacking saga, which for nearly five years lurked in the background as a celebrity media story with little relevance in the real world. That was until 2011 when revelations that journalists had hacked the phone of murdered schoolgirl Milly Dowler made its significance too important to ignore.

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This week has seen a similar step-change. In waging war on The Mail, days after condemning David Cameron for being “weak at standing up to the strong”, Miliband has pushed the debate out of the conference hall and into the real world. He is finally showing Prime Ministerial mettle.

The significance of this cannot be ignored. As the war threatens to overshadow another week, it is burying the old notion of New Labour and making the Conservative attack on “Labour’s mess” look increasingly wearisome. Public opinion is shifting too. When Miliband vowed to clamp down on energy companies, The Mail on Sunday were among the critics quick to write it off as the return of seventies socialism.

Those lines of argument are tainted. Earlier this week it emerged the newspaper had dispatched a reporter to a memorial for Miliband’s dead uncle. This in the same week that its sister paper concluded that his late father, a Jewish refugee, “hated Britain”. The outrage transcends politics.

Momentum is gathering. There has been a protest outside the paper’s offices in Kensington, advertisers are being lobbied to pull their budgets from The Mail, and complaints are piling up at the Press Complaints Commission days before a crucial Privy Council meeting that will decide the future of press regulation on Wednesday.

Then there are other matters. There is the squandered airtime that should have belonged to the Conservative party conference but instead saw New Labour spin doctor Alastair Campbell strangely redeemed and reincarnated as a BBC Newsnight attack-dog. There is the chorus of moral disapproval from party leaders on all sides of the spectrum. There is the glaring absence of Paul Dacre. And there is an apology from Mail on Sunday that, regardless of their separate operational structure, has exposed a gaping hole in the perceived certitude of the paper.

The plates of power are shifting and, with them, Miliband’s own prospects. On Syria he struggled to articulate a clear alternative to military intervention. He says he stood up to Murdoch, but that was from the safe side-lines of opposition.

This time, however, it is different. In fighting for his father Ed Miliband has finally found himself. It is this battle that has articulated his values and separated him from his party’s former leaders. It could prove to be Labour’s most potent election weapon yet.