Possibly the most striking thing about his resignation from the Labour leadership is how easy people have found it to make nice remarks about Ed Miliband without defending Milibandism.

Many have referred, rightly, to his passion and sense of personal conviction and his confident performance once the campaign got underway. Others have talked of the way he kept the party together, on the surface at least, following the leadership battle with his brother in 2010. And it is a commonplace to remark on his amazing resilience to the ugly media attacks made on him.

But, so far, I have not heard any stout defence of his political ‘project’, either from those closest to him who agreed with his determination to reject New Labour or those who were sceptical of what he was doing but nonetheless chose to go along with it.

Herein lies what, I think, handicapped Miliband’s leadership. He felt intensely lonely, unable to get across his arguments effectively or recruit enough people to help him do so. From the outset, he believed that he could count his real supporters on the fingers of one hand and that even they were prone to doubts. And, as for the erstwhile ‘Blairites’, it was only a matter of time before they came for him in the night.

So, while he insisted that the electorate had moved left following the global financial crisis and were ready for his alternative brand of state-led, interventionist social democracy, this case did not cohere or become a compelling vision of society. He asserted that he would “completely change the way the economy operates” – an appealing thought to those who felt left behind in the rush to globalisation and are giving UKIP a look – but never explained how.

He rightly pointed to the increasing gross inequalities that blight Britain but apart from proposing higher taxes on the top 1% never projected new ideas for spreading wealth, promoting social mobility or radically widening economic and educational opportunity.

Instead, Miliband fell back on a string of financial offers – rail fares, energy prices, housing rents, tuition fees, government-backed minimum and living wages and more money for the NHS – which he believed were enough for a discontented, left-leaning ‘core’ vote to give him victory and which the ‘rich’, stigmatized by his Obama-style rhetoric, would pay for.

This came to sound more like populist, transactional, rather than principled, politics. Not because all his offers were wrong but because, despite Ed Balls’ valiant efforts, they were impossible to fund convincingly and because, apart from a barely explained commitment to a new state-run banking sector, ill-defined commitments on skills and welcome devolution of power to big cities, he chose not to articulate the policies for economic and industrial growth that would pay for his policies.

To me, this vacuum at the heart of Labour’s manifesto is the greatest mystery of the last five years. Why was there not more economic weight in it? Why was Miliband so silent in critiquing George Osborne’s failure to achieve the re-balancing of the economy the Chancellor promised in 2010?

There are three possibilities, none amounting to an adequate explanation. That he wanted to transform the market-friendly ‘industrial activism’ I constructed into a more fully-fledged state-run industrial strategy but feared how this would be perceived and misrepresented. Or that turning this page would get him into a full-scale disavowal of the Labour government’s economic record on which he knew he would not carry his colleagues, in particular Balls. Or that, for all his distrust of business motives and belief that markets are intrinsically inefficient, he had simply not thought through his alternative model of ‘responsible capitalism’.

Whatever the reason, the result was that Miliband fell back on a fairness argument rather than an economic one to carry his whole message, re-distributing the cake without saying or knowing how he would make it bigger.

Interviewed in the early hours of last Friday morning, Neil Kinnock argued that Labour had lost because of the ‘false consciousness’ of economic security that the Conservatives had implanted in voters’ minds. True up to a point but who could blame the voters for deciding that the Conservatives were a safer bet when Labour was saying so little about growing the economy and that Conservative security, essentially, was the only financial security on offer ?

Either way, Labour will never be credible without convincing people of its economic credentials, that the party understands business, that profit is not profiteering but the basis of further investment, and that while markets need a framework of policy to surround them, there is not a practicable alternative to them.

Most thought that the party had crossed this rubicon under New Labour. In reality, it is not contested still by the overwhelming majority who know there are many ways that a capitalist economy can be made more efficient and fairer, and for government to provide incentives for innovation and to restrict unearned rewards.

But unless we are explicit about what we believe, voters cannot be forgiven for their ‘false consciousness’, leaving us unelectable.