Nigel Farage’s party is third in the polls, at time of writing, on 17 per cent (Populus), and we anticipate the imminent publication of the Ukip election manifesto.

We got a preview of Ukip’s health policy from spokesman Louise Bours today, including a headline-grabbing pledge to spend an extra £3bn on the NHS every year – half a billion more than Labour have promised.

As ever though, the devil is in the detail. Scalpel!

‘Health tourism… costs up to £2bn per year’

Actually the real cost of “health tourism” – in the sense of people who have travelled to the UK for the sole purpose of getting free healthcare to which they are not entitled – is actually only about £20m to £100m, according to this report from the Department of Health.

That figure of £2bn refers to the total cost to the NHS from treating all the people who are not ordinarily resident in Britain, including visitors and short-term migrants, students and indeed British expats.

These people aren’t all cheats, scroungers, illegal immigrants or people who don’t pay their bills. The research makes it clear that many of them are exercising their right to some free healthcare under various EU and non-EU reciprocal agreements with other countries.

As far as we can see, Ukip is proposing that we scrap these two-way deals and ensure that everyone who visits Britain has approved health insurance instead.

Presumably if this happened Britons would lose their reciprocal rights to free healthcare in other countries too. We asked Ukip’s health team how they saw this panning out but haven’t had a reply yet.

‘Elderly social care funded with £1bn per year’

Is that £1bn MORE than is being spent now? We presume so, because Age UK put the current annual spend on social care for the over-65s at £6.7bn.

So does that mean a full third of the extra £3bn Ukip is promising to spend is for elderly social care? We’re not sure yet.

It matters because…

‘This money will provide 20,000 new nurses, 3,000 midwives and 8,000 GPs’

…it’s not clear that £3bn will cover all the extra spending Ukip commitments announced today.

Training 8,000 GPs alone could cost as much as £4bn, according to British Medical Association figures which puts training costs at £500,000 per GP – although Ukip says it wants to coax those who have left the profession back into work, which would presumably be cheaper.

Nurses cost £70,000 each to train, so 20,000 more of them could take £1.4bn.

Then there are the salaries to be paid: about £240m year for the starting salaries of the extra 8,000 GPs, rising to perhaps £800m over time. Paying 20,000 nurses the average starting salary of £21,388 would cost more than £400m.

Today’s policy launch contains at least seven uncosted proposals: a new licensing system for NHS managers; extending GP surgery opening hours; increase funding for mental health services; increased mental health support for pregnant women and new mothers; a pilot scheme to put GPs in accident and emergency departments; scrapping tuition fees for medical students on a means-tested basis; replacing the Care Quality Commission with county health boards.

We can make an educated guess about the cost of some of these things: these academics think it would cost £283m to improve mental health services for new or expecting mothers.

But ultimately, we’re groping around in the dark because Ukip has not costed most of these policies.

‘How long do we provide a carer for an old man with dementia, to make his lunch, feed it to him, organise his medication, and make sure he will be okay for the rest of the day? 15 minutes per visit. 15 minutes’

This makes it sound like the only home care visits old people receive last for 15 minutes – but that’s not true.

It is true to say that some councils send carers for very short visits, and that this is highly controversial. But not all care appointments last for a quarter of an hour.

Last year Unison found that the number of English councils commissioning 15-minute visits has risen in the past year, despite a commitment from the government to stamp out the practice.

But the trade union’s figures suggest that only 14 per cent of the visits organised by councils last for 15 minutes.

‘Ukip pledges an additional £3 billion more for the NHS every year; an affordable sum paid for ultimately by the savings we will make from leaving the European Union’

There’s a massively EU regulation-sized can of worms here. Ukip is presuming that pulling out of the EU will be a straightforward cost-saving exercises, since Britain will stop making a net contribution to the EU budget. That contribution increased to £11.7bn in 2013.

But there are supposed to be economic benefits from membership too. The numbers are so complex, and the debate so polarised, that no one can really prove conclusively whether being in the EU is a boon to the British economy or a hindrance.

We have FactChecked this to death before – see here and here – but there is no straightforward answer. It’s fair to say that many economists disagree with Ukip’s basic assumption that leaving Europe will inevitably save Britain money.