Leading article: Miliband's big ideas - constrained by politics, history and economics

The Labour leader has three-and-a-half years to fill in the substance of the contours he drew yesterday

Of all the speeches being delivered during this year's party conference season, it was yesterday's by the Labour Party leader, Ed Miliband, that was most keenly awaited and where the stakes were highest. He had to prove that he was his own man; that he could offer an alternative to the Government in power; that his was an authentically Labour voice, and that he was no accidental leader. In looks, sound and tone, he did better than sceptics within his own party and in the country had probably feared. He bought himself time.

In much of what he said there was a refreshing seriousness, which matched the mood of the times. He was speaking, after all, on the day of an announcement by one of the country's largest employers, BAE Systems, that 3,000 jobs were to go. Nor could he be accused of talking down to his audience – whether in the hall or in the country at large. He offered the contours of big ideas.

They started with the suggestion that for more than 30 years – that is, through governments of both major parties – British politics had been on the wrong track. They continued with his determination "to break the closed circles of Britain" – a neat formulation that brought together Old Labour class struggle and more recent concerns about stalled social mobility. And they concluded with calls for a "new bargain" in the economy to ensure that wealth creators were treated differently from asset-strippers and effort and industry received their due rewards.

The difficulty for Mr Miliband – as for the shadow Chancellor, Ed Balls, in his conference speech the day before – was that, when all is said and done, the Labour front bench of today finds it simpler to differentiate itself from the New Labour of Tony Blair than it does to identify a significant body of clear blue water between itself and the Coalition. The boos from the hall when Mr Miliband mentioned Mr Blair, and the shocked reaction to those boos from other delegates, demonstrated how divisive his legacy has already become.

But Mr Miliband's grave promise that, if the Coalition failed to reduce the deficit, a Labour government would do it, and his acknowledgement that Labour would not reverse, or be able to reverse, many of the Coalition's cuts, showed his acceptance that there would not, and could not, be any return to Old Labour either. This is, first, because the money just is not there and, second, because times have changed. There is more grim realism around than there has been for a long time; what is more, it is realism that is widely shared.

Indeed, if you had shut your eyes, changed a few names, and filleted out Mr Miliband's effusive defence of the NHS, you might have been hard put to decide whether it was a Labour politician speaking or a member of the Coalition team. He even used the word "cheating" to describe those claiming unwarranted benefits. All of which leaves Mr Miliband little that could be identified as a distinctive policy platform on which to take Labour into a general election.

It could be argued that this does not matter – yet. With fixed-term parliaments now a fact of political life, Mr Miliband has three-and-a-half years to fill in the substance of the contours he drew in Liverpool yesterday. But the central dilemma remains. Mr Miliband departed from Labour thinking old and new, and presented a political philosophy that could be described as embryonic one-nation Labourism.

But that inevitably overlaps with Mr Cameron's brand of one-nation Conservatism – especially when that Conservatism is tempered, as it is, by the contribution of the Liberal Democrats and the sometimes surprising social interventionism of Iain Duncan Smith. In trying to make Labour electable again, Mr Miliband finds himself jammed between the political centrism of the Coalition and the constraints of economic reality. Within the very limited room he had for manoeuvre yesterday, avoiding failure must count as modest success.