The future of the NHS and health was fiercely debated by party leaders in Scotland in Tuesday night’s BBC Scotland debate.

Yet health is a devolved issue – meaning Keir Starmer and Rishi Sunak will never have the power to deliver on their key promises to reduce waiting times and get the NHS back on track in Scotland, Wales, or Northern Ireland.

The simple reason is polling in Scotland regularly puts the NHS among the top three issues for voters, so parties inevitably put it front and centre as they publish their manifestos.

You saw that in the debate, with an audience member recounting her mother’s experience of waiting for treatment – and each politician trying to answer what their party would do to improve the NHS.

In Scotland, the SNP government at Holyrood will continue to be accountable for the performance and priorities of the NHS after the election on 4 July.

But it’s not the case that whoever holds the keys to Downing Street will have no role to play in the future of Scotland’s health service. Just how far their responsibility extends is a matter of political debate.

The Scottish government gets a share of taxpayers’ cash collected and then sent back in the form of a lump sum or block grant.

Any UK government decision to award extra funding – or cuts – to the health service in England automatically sees an equivalent amount channelled north of the border.

However, once the funding arrives in Edinburgh, the Scottish government is free to spend the money as it chooses. In the coming year it has committed nearly £20bn to health and social care.

The most recent comparison available suggests Scotland spends 3% more per person than England in this area. This gap is much smaller 25 years ago, when Scotland spent 22% more per head of population, according to the Institute for Fiscal Studies.

More money for the NHS may be on offer from Labour or the Conservatives, some of which will come north. But they are both taking aim at the SNP’s record in running the health service, as they know First Minister John Swinney’s candidates are the ones to beat to make election gains in Scotland.

Scottish ministers are proud to point out that it’s the only UK nation to have avoided strike action by healthcare staff. It’s a record the Scottish government want to defend.

When nurses, paramedics and physiotherapists took industrial action in England, Northern Ireland and Wales, the Scottish government had already cut a deal costing £575m with unions that saw staff paid more than in other parts of the UK, with commitments to cut down hours and introduce legislation on safe staffing levels.

As England braces itself for another wave of junior doctors’ strikes this month, patients in Scotland know they are safe from that, after the Scottish government set aside £60m for a 2023/24 offer.

Despite avoiding the disruption of strikes, the latest data showed NHS waiting lists in Scotland had reached a record size at the end of March, with 690,000 waits for planned outpatient or inpatient care.

And in contrast to England, Scotland has failed to fulfil a 2022 pledge to eliminate the longest waits. More than 80,000 procedures or appointments had a waiting time of over 12 months, and 8,000 over two years.

But Mark Dayan from the Nuffield Trust says there may be good reasons for this, and that Scotland’s waiting times are not the worst in the UK. In fact, he says the NHS in Scotland and England are broadly similar when it comes to average waits for elective care.

He said: “[It] suggests Scotland’s NHS isn’t targeting the longest waiters as aggressively, which may be justifiable as long as it means that the most clinically needy are at the front of the line.

“In both Scotland and England, roughly two thirds of patients are reaching the end of their wait for care within the 18 week benchmark. Northern Ireland’s waiting times, despite some recent improvement, remain by far the longest in the UK. The average person waits nearly a year just for an outpatient appointment, whereas in England and Scotland that would be about three months.”

Neil Gray, the Scottish government’s health secretary, has said the struggle with long waits in Scotland was down to a different “tolerance of engagement” with the private sector.

Before the pandemic, the Scottish government agreed to pay private providers for extra capacity under its Waiting Times Improvement Plan. In 2022/23, NHS Scotland spent £116m on external providers (0.7% of what it calls the frontline health budget), compared to a bill of £11.5bn for the UK Department of Health (6.5%) – nine times more, according to a Scottish government spokesman.

It’s worth noting that members of the public in Scotland who face long waits appear increasingly willing to turn to the private sector. The Nuffield Trust found that the number of people going private for hospital treatment has risen 80% since 2019. In England that figure was up by just 20%, although it still remains highest relative to the size of the population.

Instead of relying on the private sector to help, the Scottish government wanted to build 10 new National Treatment Centres to tackle the NHS backlog by delivering an extra 40,000 procedures a year.

But they’ve now decided to pause capital spending with only three up and running so far, and two more scheduled to open this year.

There is no timeline in place for the others.

The Scottish government said the building projects have been paused due to a reduction in funding from the UK government.

The part of the total block grant reserved for capital spending is due to fall this year, from £6.4bn to £5.6bn. This is not just for health, and isn’t a direct cut to funding for NHS services, but Scottish ministers argue it stops them from making choices about how to spend cash to cut waiting times.

But Scotland is not completely beholden to Westminster’s decisions for funding. Over recent years changes to the devolved tax system mean that the Scottish government will raise around £1.5bn extra this year to spend as it wishes on public services.

But such choices are unavoidably political. If SNP leaders find it easier to compromise with NHS staff on a pay deal with a massive price tag it means less money spent elsewhere.

On the other hand, NHS use of the private sector is more controversial in Scotland – whereas the Tories in England are content to contract out services to increase hospital capacity.

Much of this tension played out in Tuesday night’s debate.

The current blame game between the two governments over NHS performance is intense; the SNP Scottish government says the Tory UK government gives them less money to spend, the Conservatives say that health spending is at a record high, but being squandered by the nationalists.

Scottish Labour says both the SNP and the Tories are responsible for years of mismanagement. Meanwhile the Scottish Liberal Democrats put the blame solely at the SNP’s door for failing to give NHS staff the resources they need.

This kind of political disagreement is familiar at election time, but some might ask whether it helps or hinders a struggling behemoth of an institution, responsible for the health and wellbeing of millions of people.