I'VE always had deep affection for Sam Galbraith, the former Scottish health minister, ever since I first met him in the 1980s during a factory occupation in Bathgate.

He was a fiery left-wing consultant neurosurgeon then who, like me, had an interest in climbing. As it happens, we both went on expeditions to the Himalayas around the same time - though to different places - and both came back physically the worse for wear.

Though in Sam's case it was rather more serious. He developed incurable lung disease and was given only three years to live, even after a lung transplant in Newcastle. But 25 years later, he's still going strong - living proof of his will to live, and the effectiveness of the National Health Service of which he has been a lifelong defender.

So I was saddened to see last week Sam Galbraith promoting the latest independence health scare. He said that after a Yes vote, Scots would no longer be able to have operations like his in England without "filling in forms and handing over money". As a former health minister, his claim that an independent Scottish NHS would no longer be based on need rather than ability to pay and that Scots would be denied access to health in the rest of the UK will understandably concern many Scottish voters.

Yet this is as bogus as the claim from Better Together that Scottish children would be denied care at Great Ormond Street Hospital in London, or that independence would set back a cure for cancer. These scares were rejected by both Great Ormond Street and Cancer Research UK. And the same is true of transplants. In the very few cases where radical operations have to take place outwith Scotland they are already paid for by the Scottish NHS under long-established arrangements. There is no earthly reason why this should not continue after independence.

The real danger to the NHS lies not in a Yes vote, but in the invasion of private provision in health being promoted by Westminster. The Conservative health reforms have opened up the NHS to private providers on an unprecedented scale. Healthcare is still nominally free at the point of need in England, but privatisation of care has fundamentally altered the character of the NHS.

The 2011 Health and Social Care Act led to fragmentation as private healthcare groups bought in to lucrative areas of elective surgery, leaving the state sector with the burden of looking after the manifold health demands of an ageing population. The combined effects of PFI debts and funding cuts have placed half of England's hospital trusts in bankruptcy and left many looking to private companies to take over. The Financial Times suggests that up to 30% of English hospital trusts could effectively be in private hands by the end of the decade.

In Scotland, by contrast, the last significant private hospital development, HCI Clydebank, was nationalised in 2003 by one of Sam's colleagues, the then Labour health minister Malcolm Chisholm, and turned into a national centre for clearing waiting lists. He also abolished trusts and market competition. When Nicola Sturgeon took over the health brief after the SNP victory in 2007, private provision was removed from the NHS by law and the system became what it was always supposed to be: an integrated service based on collaboration between the various layers of the service rather than a market divided by competition and contract. She completed the original NHS project as envisaged by its Labour founder, Aneurin Bevan, and abolished prescription charges in Scotland.

Many UK politicians, Labour and Tory, said that this was all folly, and that Scotland would have to introduce the English market reforms, originally promoted by Tony Blair, or else the system would collapse. Well it hasn't. The Scottish health system has rarely been more popular. According to the recent Scottish Social Attitudes Survey, satisfaction with Scotland's NHS has increased by 20% since 2005.

The claim that this would be threatened by independence is patently absurd. The Scottish Government's independence White Paper, could hardly be clearer on health. It affirms that the NHS would remain in public hands as a fully state-funded public service. However, it is difficult to see how this uniquely Scottish arrangement could continue if Westminster continues to control the purse strings.

The Scottish Parliament is responsible for health in Scotland but funding remains with Westminster through the Barnett Formula, which increases or decreases every year in line with health spending in England. The intention of the UK health reforms is to get private companies to take on more and more of the work of the NHS, reducing the contribution made by the taxpayer. This will inevitably reduce the funding that comes to Scotland, even assuming the Barnett Formula is retained. George Osborne has pencilled in a further £35 billion in cuts to health spending. As consultant surgeon Philippa Whitford has argued, this means the Scottish Government might be forced to go along the same privatisation route to fill the gap.

But there is a further threat facing the NHS. The Transatlantic Trade and Investment Partnership (TTIP) is the fruit of long-running negotiations between the EU and the US over trade liberalisation. One of its fundamental principles is that services, including state services, should be open to private competition from American multinationals. According to Garcia Bercero, the EU Commission official with responsibility for TTIP, health services in Europe will be opened to private competition, but only where privatisation is already established. In other words, where there is an existing state monopoly, foreign companies cannot sue the government in question for unfair competition.

But the UK Health and Social Care Act opened the UK system to TTIP because it explicitly introduces a private market in health provision in England. After a No vote, private providers and insurance companies may argue that, since Scotland is not a sovereign state but a region of the UK, it cannot be exempted from competition for health provision. We are a long way from that being tested in law, but what is beyond doubt is that the UK has made the NHS in England TTIP compliant. It seems highly likely that the Scottish system will be seen as an unacceptable anachronism in a unitary state.

We all owe a massive debt to the much-maligned National Health Service. It really is one of Britain's greatest achievements. People complain bitterly about its alleged inefficiency, until they find they need to use it themselves. America spends twice as much of its GDP on its privatised health and gets an inferior service. Many millions of Americans have no adequate health insurance.

The NHS was one of the great institutions of the old United Kingdom - the caring, sharing UK which now only exists in speeches from Better Together politicians and in Olympic Games ceremonies. Along with social security, regional policy and free higher education, the NHS was one of the great unifiers of the Union, and made Scots proud to be part of Britain. But this social Britain no longer exists. Westminster has knocked away the key supports through welfare reform, tuition fees and privatisation of the NHS.

The great irony of this referendum is that it is Scotland that still believes in the United Kingdom of welfare and social solidarity. It is England, led by Westminster and the City of London, that is discarding it.