Tony Blair remains a conundrum of modern politics: the thoroughbred election-winner reviled by his own party in his afterlife. His thoughts on the positioning of modern parties, their outlooks and weaknesses remain far better heeded abroad than at home. If his stardust looks tainted in Britain, it still shimmers abroad.

So as François Hollande’s embattled socialist government totters on in France, its economics minister Emmanuel Macron cites an ur-Blair recipe as his year-end inspiration. “By the time Tony Blair pushed the change through [dropping the clause IV commitment to public ownership] few people really believed in nationalisation,” Macron says. “But it was symbolic; it demonstrated how things had changed.” By the same token, education reformers from Mexico to the Middle East and Asia hang on the words of the man who started the overhaul of comprehensive education and created a sustainable university funding system.

In Britain, Blair faces a comeuppance year for his prosecution of the Iraq war. Even those who do not decry every western leader who wants to unseat murderous despots as a deranged warmonger can see that the Chilcot inquiry will most likely deliver a rough assessment of the handling of the case for war, the inward-looking nature of “sofa government” and how poorly counter-arguments to the case for weapons of mass destruction were treated. I suspect that Blair, a master of timing, wants to air his beliefs before the storm breaks. That might also account for his bullish mood on the two occasions I met him recently to prepare an article for the Economist.

Nowhere was this more apparent than on British politics and the Labour party. He says that he “hopes” Ed Miliband wins in May, but draws a distinction between himself – “I am still New Labour, I always will be” – and Miliband, who he thinks is not. (Ed would quite happily sign up to that, given that he has conceived of his leadership since day one as anti-Blair in style and much substance.)

Crucially, Miliband’s predecessor at the Labour helm fears that unless the party positions itself much more clearly in the centre ground, 2015 could see a general election “in which a traditional leftwing party competes with a traditional rightwing party, with the traditional result”. (For the avoidance of doubt, he was also clear that this would mean a Tory victory.) The centre, Blair added, had not moved in the wake of the financial crisis, as some suggest. Or if it had, it had tilted rightwards. He evidently dislikes the tendency by Camp Miliband to talk about business in Britain as if it were little more than the setting for perfidious economic crimes.

This vigorous defence of third-way positioning also set me wondering if we know what the political centre is, other than a place moderates lay claim to (I am in the centre-ground; you lurch to the right/left; he or she is a swivel-eyed lunatic). Blair ponders why, when so many voters are “liable to group around the centre”, parties in Britain and beyond have abandoned it. Conservatives move rightwards on signal topics such as immigration to regain voters attracted by Ukip; Labour dims its public-sector policy offering into a list of things it wants to rewind, set in aspic or spend more invisible money on.

This irks reformists, myself included, who side with Don Quixote in recommending that we should not go looking for the birds of tomorrow in the nests of yesterday. However, Blair may also be prone to a bit of yesterday-ism when it comes to his belief that voters are presently crying out for a moderate offer which the big parties are denying them.

Rick Nye, managing director of polling organisation Populus, carried out some ingenious research not long ago, testing how a sample of voters reacted to subjects classically regarded as defining whether people regard themselves as to the left, right or somewhere in between. Centrists can take comfort that there was support of about three-fifths for EU membership and the view that immigration was broadly a good thing.

Not such good news for Blairites, or indeed moderates of any persuasion, was that the groupings of ideas that represented a starker left or rightwing prospectus, when aggregated, attracted more support than the centrist alternatives. Populism, whether of the left or rightwing variety, turned out to be more appealing than the compromises represented in the middle ground.

The most successful of these “virtual” offerings wanted Britain out of the EU, less immigration and thought that climate change arguments were exaggerated. Both left and rightwingers in the Populus examples were worried about globalisation and, far from agreeing with Blair’s view that it is “generally a force for good if governments handle it well”, wanted governments to do more to combat it.

In other words, voters are keen on positions that are extremely hard, if not impossible, to deliver and which ignore many of the dilemmas of running a moderately sized, prosperous but overspent country with high expectations of what the state can deliver in the 21st century. Who is going to deal with that? A hardening of views seems to have taken place to the right and left, and not an especially promising one.

But let us not forget another bit of Blair’s legacy and the main headache for Miliband as we tiptoe into election year. Parties do not offer de-branded concepts: they are a blend of ideas and personalities. While Miliband looks closer to a range of preferred attitudes on paper, he has yet to seal the deal with voters that his form of Labour government would solve their problems.

This is the first and most important pre-election tussle of 2015. But the big argument that the Blair test revives will continue long after May. The centre ground sheds its appeal and capacity to produce new ideas when there are too few politicians with the grit and stubbornness to articulate a vision of what it should be.

That is a big miss at a time when technological change and a more competitive world can push people to retreat to an outdated, chippy collectivism or the false comforts of narrow nationalism. Beyond Blairism, it is the real gap in British politics across the parties – and its most tempting vacancy.