The worst-ever winter crisis, growing public dissatisfaction with longer waits for A&E care, GP appointments and cancer treatment and a desire to fulfil the Brexit battle bus’s pledge of £350m a week more for the health service mean the question facing the government is not if the NHS gets more cash, but how much more.

In fact, the debate behind the scenes is whether the NHS should get a lot more money or an awful lot more money to mark its 70th birthday on 5 July. Of course, both terms are relative to the paltry 1% annual increases since 2010 that have contributed significantly to the service’s increasingly visible deterioration. As we prepare to celebrate Attlee and Bevan’s glorious creation, a seismic shift in Tory attitudes is under way.

Curiously, the minister most responsible for this long overdue rethink is Jeremy Hunt. True, the health secretary is the one who many NHS staff view as having done the most to hasten its decline, while blaming everyone but himself. Who, amid the fallout of the junior doctors dispute or him pretending that another 1% rise was generous, would have predicted that he would have lasted longer than any other health secretary ever?

But in the last few months, Hunt has quietly but radically changed his position on the NHS. After so long in the job, he seems to finally understand the huge pressures it is under and adopts critical, kneejerk stances a lot less. For months now senior doctors, NHS bosses and health thinktankers have been struck – in private meetings with Hunt – by his candid recognition that eight years of austerity funding have left the health service unable to cope; that the crisis in staffing, with 93,000 vacancies in England alone, is even more perilous than the lack of money and that the austerity-era financial straitjacket must be removed urgently.

It is an improbable transformation: from stern critic of the NHS, alienator of its staff and overseer of a disastrous slide in waiting time target performance, to the service’s possible saviour in its time of acute need. The very notion will appal many people. But that doesn’t stop it being true. Consider this. Hunt has argued for a long-term funding settlement for the NHS since December. Come March, May duly committed herself to delivering exactly that. In meetings at Downing Street and with Cabinet colleagues he has been determinedly arguing the case for the NHS to receive as close as possible to the 4% a year rises it got before 2010 .

To the consternation of a Treasury ever cynical about the NHS’s appeals for more money, Hunt appears to be winnng the battle for May’s ear, telling the Guardian last week that her 70th birthday gift that would involve a “significant increase” in its budget. Without his backstage lobbying and skilful use of the media to assist his cause, the NHS may have been condemned to even more austerity. Does Hunt hope splurging the cash now will detoxify the NHS as a Tory weak spot by the time of the next election in 2022? Almost certainly. Is his new‑found mission to save the NHS a pitch to become prime minister? Possibly. But, frankly, who cares? All that really matters is that the service’s unlikely new champion prevails in the ongoing battle with the Treasury – the NHS’s future depends on it.

• Denis Campbell is the Guardian’s health policy editor