Sir Bruce Keogh, medical director of the NHS, has just completed a forensic report into 14 underperforming hospitals which is already hailed as the cure for many of the health service’s well-publicised ills. The next thing on his to-do list is a long-awaited review into the small matter of Britain’s A&E crisis.

Throw in the biggest budget crisis in the NHS’s 65-year history and constant scrutiny from the media, and one might expect to encounter a man beginning to feel the heat.

Apparently not. Leaning back in his chair, collar undone, in an airy meeting room at NHS England’s clinically clean London headquarters, Sir Bruce appears entirely unruffled by the bitter row sparked by his recent report.

“I felt relaxed about that debate [in the House of Commons]” he concludes. “You can’t take politics out of the NHS … but what you can do is shield the front line from the politics. You can free up the professionals and let them get on with running the NHS while the politicians set the direction.”

For a full week earlier this month, the fallout from the Keogh review into hospital deaths dominated front pages. First, Sunday newspapers reported that his review would condemn the 14 hospitals for causing 13,000 avoidable deaths. The figure set the political weather, allowing the Health Secretary Jeremy Hunt to position himself as the patients’ champion straightening out a health service left in a dangerous state of disrepair by Labour.

Then, on the day of the report’s publication, it became apparent that the figure was inaccurate – and Sir Bruce had never used it. A leaked email revealed his disdain for the newspaper stories, and before he knew it, the Labour Party also had political ammunition; accusing the Conservatives of “portraying the NHS in the most negative light it possibly can” in order to support “privatisation and marketisation of the NHS”, to quote the shadow Health Secretary Andy Burnham.

But with politics firmly back in its place for now, Sir Bruce retains the cool reflection of a born doctor.

Born in Harare, Zimbabwe, Sir Bruce is six years younger than the institution he fronts. He came to England aged 19 to study medicine in London, rising to become one of the country’s leading heart surgeons and a pioneer of making surgical performance data public.

Although he may be laid back about the politics, he has no illusions about the seriousness of the NHS’s current condition. “Given the constraints on the money of the NHS, the clock is ticking,” he says, in reference to a slow-down in Government spending that will become a £30bn funding black hole by 2020.

“We have to change dramatically if we are to retain everything we are proud of in the NHS. I don’t think everyone recognises the urgency. I think sometimes, when there is a really difficult challenge ahead, some people find it easier to ignore it. But this is really significant.”

Exactly what that change will look like, Sir Bruce confesses, is not clear yet. Efficiencies have been made and more will follow.

“If you go down to PC World or Dixons, each year you would expect to pay less for a PC and you would also expect the specifications to improve,” he says. “I have all sorts of people [in the NHS] saying to me: ‘Give me £1,000, give me £200,000; I can improve our service’. My challenge is every other aspect of industry has to improve the quality they offer for less. So we need to change that mindset.”

Services will be concentrated in fewer more specialist centres, but that does not necessarily mean some hospitals must close.

“People still need to be in hospital but I’m not sure we always have people in the right hospital with the right expertise,” he says. “In many of our hospitals, if we had better community care and social services, we could get 25 per cent of patients out. It’s that order of magnitude.”

He is pragmatic, but not without the glint of idealism. He is animated when asked if, under such pressure, the NHS can survive in its current form, free at the point of need.

“While I am medical director I can tell you I will fight to absolutely protect that principle [of free, public healthcare],” he says. “Three things distinguish a civilised society: its approach to science, its approach to the arts and how it looks after the most vulnerable members of society. If we give up on that third that will be a really sad day.”

The threat is real. Only a day before we meet, a survey found that more than half of GPs now believe the pressure on their practices is so great that charging patients is the only way to make them sustainable.

Sir Bruce’s message to them is firm. “I can understand why they’re saying that – but I disagree with them… If GPs start to charge does that mean everyone starts to turn up at A&E? Then do we start charging at A&E? You’d start a cascade of reactions which would challenge the very fabric of our NHS.”

Old-fashioned idealism is something he wants to see running through the NHS again – but he believes its junior doctors who are best placed to spread it.

Immediately after our interview he is meeting a group of young medics he has been mentoring through an NHS leadership trainee scheme. He has been outspoken about the role young doctors can play as “agents for change” within the health service and I ask him what words of advice he would offer the new cohort of newly qualified medics, who start on the nation’s hospital wards one week from now.

“They must never underestimate the privilege that is being bestowed on them by becoming doctors who have an ability really to help people at times of their lives when they most need it, a privilege which is bestowed on very few others,” he says. “They will all be coming into the NHS with high expectations and high values. They must, under all circumstances, hang on to those values because that will be their rock throughout their career.”

Fired up, Britain’s top doctor heads off to meet the next generation.

He is ready for a fight to protect the NHS – and he’s determined that they will be too.

CV: Sir Bruce Keogh

Sir Bruce Keogh was born in Zimbabwe, in 1954. He went to a Catholic boys’ school before coming to England to pursue his dream of becoming a heart surgeon.

He began his professional career as a cardiac surgeon in Hammersmith Hospital in 1980. In 2003, he was appointed professor of cardiac surgery at University College London and went on to hold senior positions on the Royal Society of Medicine and Royal College of Surgeons. In 2005, he was knighted.

Sir Bruce was made Medical Director of the NHS in 2007 and was reappointed Medical Director of the NHS Commissioning Board in 2010.

He has recently introduced a competitive league-table system where consultants’ results are published by all hospitals.