Leading article: A leader for the post-New Labour age

Ed Miliband secured the Labour leadership by the narrowest of margins, and his first instinct was, rightly, to extend a hand to the 49.35 per cent of the party that had preferred his brother. But the early messages he sought to convey went beyond a simple effort to unite the party around him. He said much that Labour, and the country at large, needed to hear.

His first point was that he would be his own man, "not Bob Crow's man". That Ed Miliband outpolled David thanks largely to the votes of trade union members gives the Conservatives a stick with which to beat him, and it is one they lost no time in applying. Being "in hock to the unions" is bound to be a charge that dogs the first months of his leadership, but it will attach itself to him permanently only if he allows it to. He has to show that he will not let the trade unions dictate to him, but also that he will not dismiss out of hand the legitimate concerns of the people they represent.

His second point, distinct from the union question, was that he will speak for the mainstream and not take the party sharply to the left. This required a degree of repositioning – less because of what he had actually said during his campaign than how what he said then had been perceived. Hence his promise, an echo of Blairism, that the party would be on the side of the "squeezed middle" and "everyone who has worked hard and wants to get on".

His third point, though, was to turn his back on the Blair-Brown inheritance and insist that he represents the future: "a new generation that understands the call of change". That is a useful formulation, signifying – as it does – a desire to move on, rather than demolish. As he put it so emphatically yesterday, "the era of New Labour has passed".

And a fourth point, from his victory speech, was that he would not oppose the Coalition for the sake of opposing; he would pick his fights. In so saying, he is emulating David Cameron's approach when he first became Conservative leader, but also – in the new context of coalition government – wisely not seeking to make enemies gratuitously.

The danger here is that Ed Miliband's Opposition could lack definition and bite. His support for electoral reform and a graduate tax, along with his acknowledgement that, even under Labour, there would have been public sector cuts, leaves quite a hole where points of disagreement might be. The task will doubtless become easier after the results of the Comprehensive Spending Review have been announced, but as Opposition leader, Mr Miliband must be able at once to attack and to present a reasoned alternative.

The rejection, albeit narrow, of the elder brother, also says something about where Labour does and does not want to go. While Ed Miliband successfully courted trade unionists, this need not be the sole explanation for his victory. David was the heir to Tony Blair; he was associated with New Labour and the Iraq war. He had twice dithered about challenging for the leadership, and his public manner could be awkward. David now has hard decisions to make. As someone who staked so much on becoming leader, it might be better if he now envisaged a future outside British politics.

In what happens next, much will depend on the elections to the Shadow Cabinet. But the party is now Ed Miliband's to shape. And he has much, beyond victory, on his side. After a thrashing at the ballot-box and years of destructive rivalry at the top, Labour is in a mood to unite. His will be a different party from the one it might have become under David Miliband; potentially fresher, more forward-looking and imaginative. The immediate task, though, is opposition. What the past decade has shown is the desperate need, in our parliamentary system, for a strong and purposeful opposition. Ed Miliband will be judged by his ability to provide it.