THE Scottish National Party have warned voters about a “wholesale privatisation of the NHS” and demanded constitutional guarantees that the service will not be sold off to foreign private interests. The Conservatives accused the SNP of spreading “baseless scare stories” and “unwarranted smears” and insist that the UK government is committed to keeping the NHS “free at the point of use”.

Sounds familiar? Those quotes were culled from the independence referendum campaign in 2014. Then as now, the NHS became the big domestic issue in a campaign which was supposed to be about a big constitutional issue. The NHS is the flexible friend for anti-Tory politicians – it is always under threat.

The issue took the SNP rather by surprise back in 2014. The NHS suddenly emerged in questions from the audience during the second Big Debate on independence between Alex Salmond and Alistair Darling on August 24th in Glasgow. The then leader of the SNP homed in on it like a heat-seeking missile. With typical Salmond chutzpah he devised “a new Declaration of Arbroath, which would “protect our publicly-owned, publicly-run NHS forever from Westminster privatisation and cuts”.

Labour pointed out that this was somewhat unnecessary because the NHS was already devolved to the Scottish Parliament. Indeed, the then Health Secretary, Nicola Sturgeon, had recently closed the last NHS private treatment centre in Scotland at Strathcathro in Angus. But the NHS scare worked for the Yes campaign.

This week, and not for the first time, Jeremy Corbyn has borrowed from the SNP playbook in exploiting NHS fears for all they are worth. The Tories are planning to flog the NHS to US health care, he says, without any obvious justification.

“Our NHS is not for sale” has become one of Labour's key election slogans and polls suggest it is working. The NHS scores even higher than Brexit now in many surveys of voter priorities. Twitter is filled with stories of people dying because of Tory cuts.

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Mr Corbyn claims, with more justification, that negotiations with big US pharma companies have already started, with a view to increasing NHS drug prices as part of a Donald Trump trade deal after Brexit. The presence of the Donald at the Nato summit in London was a perfect opportunity for the Labour leader to challenge him on it.

However, the POTUS insisted yesterday that he's just not interested. He “wouldn't buy the NHS if it was offered on a silver platter”. This is hardly a surprise, since he believes the US private service is superior to the “socialist” NHS. The idea that the US would actually want to buy the NHS was always ridiculous.

However, the real issue is the claim that Trump will use trade negotiations to bump up drug prices. In June, he said that “everything is on the table” in post-Brexit trade negotiations with the UK, though he later excluded the NHS.

Labour claims stem largely from the stack of official UK trade documents party researchers found last month on Reddit. In an amusing sidebar, there are now suggestions that these documents were leaked by Russian disinformation websites. Perhaps the Guardian's Carole Cadwalladr, who has long argued that Jeremy Corbyn and his aide Seamus Milne are pals of Putin, will investigate.

But whatever the circumstances of their appearance on Reddit a month ago, there's no doubt that Labour's pile of 440 redacted trade documents are genuine. They did indeed indicate that preliminary talks had been conducted between the UK and US officials on a trade deal.

One of the key issues for the US is the price of drugs because the NHS gets them at a big discount. US patients have to pay a lot more for the same medicines. This is largely because the NHS is one of the biggest health care providers on the planet and can strike a very hard bargain.

The key US proposal in the talks is that patents should be extended so that the US companies can keep the price higher for longer. Once patents expire, the price of generic drugs, like the heart drug statins, falls rapidly as other companies start to copy them.

It is no surprise that this is what US drug companies want and it stands to reason that these will be pushed by the Americans in any post-Brexit trade deal. However, it is a different matter to claim that the UK government has already capitulated. As Channel 4's Fact Check service pointed out, when it examined the Corbyn documents, there is no evidence "that proves the NHS drugs bill is to increase dramatically”.

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It all goes back to the suspicion that the Conservatives want to dismantle the NHS. It's just what people believe. Dogs bark, cats miaow and the Tories want to privatise the NHS. Boris Johnson can talk about 40 new hospitals and unprecedented increases in health spending, till he's blue in the face, but voters will suspect his motives. Yet, historically, it's arguable that Labour has actually been just as fond of private provision as the Tories.

Many of the public-private initiatives, from PFI hospitals to outsourcing of services to private companies like Virgin Care, started under Labour governments. In 2006, Tony Blair said he wanted the private sector “to provide 40% of NHS operations”, as he welcomed 11 private health care providers into the “NHS family”. The Tories built on Labour foundations with their Health and Social Care Act in 2012.

Insecurity about the NHS is understandable. It is a unique institution, very close to the hearts of British voters, who naturally suspect that private providers want to get access to it. It is easy to raise fears for its future as the UK leaves the European Union, even though as things stand, drugs are more expensive in most EU countries.

And what has also gone largely unnoticed in this election is that the US is already conducting a trade war with Britain, even while we are in the EU. As part of its retaliation for what the US claim are unfair state subsidies to Airbus, Scots whisky, shortbread and lambswool clothing have already been placed on the UK hit list. Whisky tariffs went up 25% last month.

Whether you are in or out of the EU, the US takes no prisoners when it comes to trade.