It isn’t often that you find a proposal by Jeremy Corbyn with a commanding lead in a Daily Telegraph poll, but there it is: at the time of writing, his plan for a ‘National Education Service’ is backed by 70 per cent of some 600 respondents thus far.

Which is a shame, because an NES is a really, really terrible idea.

Corbyn is explicitly modelling this on the NHS, amongst the last of the great Attlee nationalisations still standing. He writes on LabourList that: “A National Education Service would be every bit as vital and as free at the point of use as our NHS.”

To which the first response must surely be… really? Does the Member for Islington North seriously believe that you need lifelong access to education as much as you need it to medical assistance? That seems a stretch.

Beyond that though, the NES sounds like a fresh incubator for some of the worst instincts of the British left.

The first of these is a deep-seated antipathy to plural provision and user choice in public services. An NES could easily be used to effect the wholesale annexation of education providers by the state, much as the fledgling NHS gobbled up most of Britain’s independent and charitable hospitals.

Such centralisation would make it far easier for Labour, and their allies amongst the education establishment, to pursue producer-first reforms such as cutting back on objective outcome measures like league tables, forcing children into bad but under-subscribed schools, or undermining university entry standards.

As I set out on CapX this morning, pluralism is essential to making our public services more cost-effective, consumer-responsive, and quality-focused. An NES would be a profound step backwards.

The second major error is one shared by all those who believe that higher education should be ‘free’: that there is no such thing as money ill-spent that is spent on education. This is a very expensive mistake.

The Telegraph piece is a little light on details, so we don’t know exactly what ‘cradle to grave’ access to learning would entail. But either it will be rationed, or it won’t.

If unrationed, then an NES would just be supercharging the flaws of Tony Blair’s drive to cram an ever-increasing number of school leavers through university.

These include: a ‘graduate premium’ that in truth exists only for a minority; a market flooded with graduates, producing a needless barrier to entry for what never used to be graduate jobs; and young people assuming small mountains of debt with little or no payoff.

If your solution to the debt issue is just to have the Government pay for it, you’re missing the point: if someone isn’t getting a return on their degree, that degree wasn’t worth paying for at all.

Making people pay for their own post-mandatory education makes it much easier for them to make an informed, cost-benefit decision – and much more likely that they’ll do so.

This is a good thing: remember, the opportunity cost of someone drifting to university by default is missing out on several years in a vocational programme or on-the-job training which might have suited them better.

Of course, we don’t charge people for the NHS – but the NHS largely self-rations on the basis of acute, demonstrable need. If you’re sick, you’re treated. You don’t just get carte blanche to avail yourself of precious NHS resources.

Will Corbyn’s NES have some form of gatekeeper fulfilling the function of the GP and the admissions clerk, assessing the worthiness of applicants to precious NES places?

A lot of the freedoms students take for granted now, such as the ability to choose their course and place of study, are justified in that higher education is viewed as a private good and the responsibility of the student.

Without either rationing or market incentives the state will end up wasting huge amounts of money on qualifications that benefit neither their recipient nor the economy.

Universities too will face substantial changes: how long would an NES tolerate their restricting access to an ‘essential service’ on the basis of ability, as UCAS does? How much of their institutional independence and distinctiveness will they manage to hold on to as government sweeps in?

The National Education Service embodies the worst of the regressive strain of Labour thinking the Corbyn campaign represents: a huge power grab by the state that will either be prohibitively expensive and destroy incentives for responsible consumption on the part of recipients, or sharply erode diversity of provision and user choice in an attempt to replace market dynamics with centralised rationing.

The left-wing leadership challenger claims to be building on the legacy of Tony Blair. Yet the former Prime Minister’s true achievement was embarking on decentralisation of public services, and Corbyn wants nothing to do with it.