NO prizes for guessing the theme of Ed Miliband's speech to his party's conference yesterday: one nation.

The Labour leader managed to slip in those words no fewer than 46 times.

It is a handy political idea, though not an original one. Most generally it is associated with the Victorian Prime Minister Benjamin Disraeli, the founder of what became known as "one-nation conservatism". It is the idea that the country is divided between two nations, rich and poor, and that it is up to politicians to bridge the gap. Mr Miliband used the notion as a broad brush to sweep up what he saw as everything that was best about the British, from the fight against fascism to the success of the London Olympics and the UK's medal hoard, raked in by a multi-cultural Team GB that included both the Queen's granddaughter and a Somali refugee. This long "walkie-talkie" speech, delivered on the hoof and largely without notes, was more than an impressive feat of memory. It was by far his most accomplished oratorical performance to date and had the feel of a man who has found some self-belief.

It went down a storm in the hall. The test will be whether it makes an impact on an electorate that has failed to warm to him, let alone view him as prime ministerial material.

It is possible that yesterday may mark a turning point in his political fortunes. Last year's conference speech was intellectually smart but lacked passion. If anything, this one was the opposite, even if his central theme smacked somewhat of motherhood and apple pie. (After all, nobody would advocate a two nation philosophy.) But the theme was well-chosen because it coincides with an acute awareness of the way Coalition policies are driving widening inequality.

Of course, one nation was also a handy peg on which to hang his assertion that it is up to Labour to save the Union, arguing that the UK is at its best when it acts together, whether that involves fighting Hitler or tackling youth unemployment. Indeed, the young woman he encountered who had sent her CV to 137 employers and received not one reply could as easily be Scottish as English. For Scots, the problem with this speech was that the two biggest policy ideas – revamping vocational qualifications and reversing the reforms to the NHS – do not apply north of the Border. That left some rather vague threats to break up the big banks and curb the greed of hedge funds. The single throw-back to last year's speech was the reference to "producers and predators". It is still unclear how he would distinguish the two and encourage the former while constraining the latter.

Mr Miliband was careful not to promise what he cannot deliver or commit Labour to detailed policies so far in advance of the next General Election. It would be unrealistic to expect him to say what cuts he would reverse and what taxes he would raise to pay for them. Instead, this was the Labour leader claiming the middle ground in the clear and certain knowledge that it is crammed with disgruntled former Tory and LibDem voters. In Scotland, however, he will have to take on Alex Salmond, and the fight will be over Britain's constitutional future.