On Thursday, the British Medical Association began to send out strike ballots to England’s 45,000 junior doctors. If you believe one online survey, 71.4 per cent of them would rather move abroad, take up locum work, or quit medicine entirely if Jeremy Hunt, the Westminster Health Secretary, imposes a new contract.

In Scotland, meanwhile, junior doctors are in short supply. Back in August, the Royal College of Physicians and Surgeons of Glasgow disclosed that 16.6 per cent of those who graduate in medicine from Scottish universities end up overseas within three years. The resulting problems for general practice, in particular, have been well-publicised. But Scotland (like Wales) is having nothing to do with Mr Hunt’s new contract.

Shona Robison, the Health Secretary, has been clear about that. The week before last, describing her English counterpart as “wrong-headed”, she said Scotland’s “doors are open” to doctors. “Our NHS is a welcome home to junior doctors and experienced consultants from wherever,” said the minister, explaining that efforts were being made to recruit “across the UK or Europe and beyond”.

On the face of it, that’s nothing out of the ordinary. Recruitment is always a competitive business. Equally, given that the Glasgow college also drew attention to the fact that around 100 of 850 to 900 graduates in medicine return immediately to England each year, you could say Ms Robison is only seeking to redress the balance. With the Royal College of General Practitioners predicting a shortage of 900 GPs in Scotland by 2020, it would make sense.

This, though, is the NHS. It is supposed to be one of those British things, replete with values held in common by all, to be celebrated as such during Olympic Games opening ceremonies. Those who set store by that brand of symbolism invariably have the health service on their list, alongside royalty, language, the BBC, and remembered wars. The idea that difficulty in one part of the NHS could be an opportunity for another does not sit well with the rhetoric.

The symbolism rests on a half truth, in any case. The NHS in Scotland was an independent entity from the start, born in a country that knew all about state-funded health care even in 1948. Equally, there is nothing new about rivalry for recruits. Whether English juniors will flee north depends, meanwhile, largely on Mr Hunt. As thing stands, he is doing an excellent job on Ms Robison’s behalf, but we don’t know how many of the 71.4 per cent mean what they say, or if they mean Scotland rather than Australia.

The potential remains, nevertheless, for another addition to the ever-growing list of devolution’s unintended consequences. To my knowledge, Mr Hunt has yet to comment on Ms Robison’s attitude to his reforms, or on the parallel situation in Wales. If he believes that his “24-hour NHS” is truly essential, and not just a way to squeeze more work from overworked doctors at no added cost, presumably he also believes his Scottish and Welsh colleagues are guilty of serious neglect.

That would count as another unintended consequence. If the public begins to recognise that “our NHS” is actually (and increasingly) several distinct services, the temptation to contrast and compare will grow. It is one thing for a politician to grasp that he tampers with the NHS at his peril. It is a lesson Tories have to relearn time and again. But what happens when every statement is qualified? “Which NHS?” is a question Mr Hunt has not acknowledged, far less answered.

No doubt he understands reality well enough. Scotland, England, Wales and Northern Ireland do different things in different ways. They pursue different priorities, make different decisions, succeed or fail to differing degrees. It’s not clear, however, that the same understanding governs the popular imagination. The vague notion in England that somehow “Scotland gets more” has not, for one thing, led to obvious questions. Is it true? If it is true, why is it true?

Thus far, evidence from angry junior doctors in England is anecdotal. Perhaps they, too, don’t really know too much about NHS Scotland beyond the fact (if I’ve understood the BMA literature) that basic salary bands are already slightly better here than in the south. Perhaps some might respond to an ethos: no prescription charges; no NHS hospital car parking charges; a presumption against privatisation. Perhaps they would prefer anything, even the chilly north, to what Mr Hunt has in mind.

If any of that is remotely possible, the political consequences will be interesting, let’s say. Last week, a BMA spokeswoman talked of the risk of a “two-tier health service” if the Westminster health minister provokes an exodus. How many does it take to create an exodus? “Two-tier” is a faulty phrase to describe the kind of divergence that might occur. Junior doctors leaving England for Scotland would in any case only confirm an existing reality. But it would not require many leaving to give Mr Hunt the kind of headache for which aspirin is not prescribed.

The irony is that “our NHS” was one of the totems in the Unionist referendum case. An emotional investment in the idea of the service was offered to us repeatedly as one of the things binding Britain together. Dissent from the majority version by doctors at its heart would cause practical and political problems. Should Ms Robison get her wish, she can expect to be a centre of media attention.

It might not come to that. Mr Hunt could yet prevail, despite arguments that are preposterous even by his standards. He wants the juniors to believe that only one per cent of them will lose out from his contract and 75 per cent will be better off while the overall financial picture remains the same: try that sum in your head. For the doctors, nevertheless, years of work and dedication are at stake. Emigration is almost as big a step as leaving medicine entirely.

The prospect remains, nevertheless, of health professionals in flight from the consequences of a Conservative manifesto promise. That some might flee to a version of the NHS run by a government determined to secure independence from Britain only deepens the irony. In whose hands was the service supposed to be safe? This weekend, England’s junior doctors have a view on the question that was not predicted in all the referendum arguments.

Should a disenchanted English junior be reading this while contemplating the ballot paper, bear in mind that NHS Scotland is some way short of perfect. It is also some way short of being a debt-ridden disaster zone, like so many foundation trusts in England. You can, as Ms Robison might say, take your pick. Mr Hunt might wish to remember that voters can do the same. If nothing else, he should correct himself when he talks, as he does, of “the” future for the NHS. There can be more than one.

Devolution’s unintended consequences are like that. In the beginning, the basic idea was that Scotland should make its own choices, the better to meet its own needs. When people in England begin to ask about the differences, they too will wonder, like their junior doctors, over choices.