For two whole years, Ed Miliband has had to wrestle with the perception that he was somehow a pretender; the wrong leader, thrown up by a flawed electoral system; a ruthless younger brother who dared to usurp the elder's birthright. Yesterday, he stepped out of those shadows and strode forth as his own man. If Labour wins the election in 2015 – which cannot, as viewed from the Coalition's mid-term, be excluded – his speech at the 2012 party conference has every chance of being judged the turning point, for Mr Miliband and for Labour.
The immediate task he faced yesterday was to bridge the gap between the double-digit poll lead Labour has built up over the Conservatives, and his own personal ratings which lag behind those of David Cameron. He had to overcome the sense, even among many Labour supporters, that he simply did not carry conviction as a prime minister-in-waiting. Of course, by no means every future prime minister has looked the part in opposition; assuming office confers its own aura. But the big disparity between the party's poll fortunes and Mr Miliband's own could not but be a destabilising factor.
With his newly confident delivery, a compelling back-story – of immigrant parents, modest beginnings and success courtesy of hard work and the welcome afforded by post-war Britain – the Labour leader reintroduced himself not just to his party, but to the voters. Whether he should, or even could, have applied such a personal touch before is a moot point. But the more interesting, original and effective aspect of his speech was less the biographical detail than his central theme of One Nation Labourism.
In opposition, David Cameron dared to reach to the left of New Labour to steal the party's claim to stewardship of the welfare state and built it into a pillar of his election manifesto. Iain Duncan Smith, who immersed himself in the troubles of "broken Britain", became the face of policies that were sold as "compassionate conservatism", tough but fair. The message won over voters perturbed by antisocial behaviour, benighted estates, and families where three generations had never worked. The policy may not have turned out as many hoped, but it left Labour thoroughly outmanoeuvred.
Ed Miliband ventured something similar yesterday, but still more audacious. He hijacked not just one strand of policy, but a whole philosophy. He marched into prime Conservative territory, on the back of the successful Olympics, and stole Mr Cameron's claim to One Nationism. In so doing, he gave Labour an idea that has every chance of surviving until the election; he also challenged Mr Cameron's right to exemplify the brand.
The One Nation Labour theme is ingenious on two counts. First, because it removes the temptation to campaign negatively on class – a tactic that has proved singularly unsuccessful for Labour in the recent past. And second because it can be attached to any area of policy or personality, continually undermining Mr Cameron's already discredited boast that "we are all in this together".
It also obscures the fact that even the relatively few policy areas Mr Miliband developed yesterday – vocational education being one – derive to a large extent from existing Coalition policies, rather than striking uniquely Labour ground. That is one weakness the Conservatives may exploit next week. But Mr Miliband's tour de force left him looking stronger, and the Conservatives more vulnerable, than either has looked at any time since the last election. If Mr Cameron wasn't worried before, he should be now.