“Horrible decisions will be made about who lives and who dies,” says the chief executive of a large hospital trust. “And I will be the one to make them. Liability sits with me.” This manager, somewhere in England, dare not say who he is – “Everyone is under a total media blackout” – but he doesn’t think silence a good policy. “Any vacuum will get filled by Twitter or the Daily Mail.”

He has done the sums locally: he has 130,000 over-80s. He follows chief medical officer Chris Whitty’s high estimate of an 80% infection rate, with 10% needing a bed and 4% intensive care. Even extending his 15 intensive care beds, he will never have enough. His staff are anxious, needing to know every detail of what’s going on as he patrols his corridors.

“The truth is we won’t cope. No one will. This is real. We will all get it and I just hope we won’t all get it at once.” He adds: “I’m dying to get it soon and get it over with.”

Because those “horrible decisions” loom ahead darkly, he has set up an ethical group to advise him. He has recruited a senior cleric, a respected headteacher, several doctors and some lay people who are trusted in the community to consider the terrible choices ahead. “They will advise, but I know the final decisions sit with me.” And very final they will be.

The NHS manager I spoke to fears that 'blitz spirit' early on will soon give way to an outraged, 'But that’s my grandma!'

NHS England has sent out letters to GPs on triaging patients into three categories, with only the most serious to be admitted to hospital. What the guidance doesn’t yet spell out is all the criteria. It’s easy to assess medical conditions, but after that come tougher choices. In Italy, ventilators have been restricted to those under 65, priority given to the young. We, with many fewer beds, are still a few weeks behind them.

Later come the political questions of how the country came to be left so nakedly unprepared – the NHS and social care brutally worn down by a decade of needless, ideologically driven austerity, with local government and civil service stripped of experience and capacity. We are where we are, right now. Public services will no doubt do their heroic utmost, often in appalling situations.

In this context, the decision to save the young before the old is, without question, right. Who comes first, the pensioner or the young parent? The one mercy of this virus is that it seems to pass over children. That’s a comforting thought for we grandparents to bear in mind if we find ourselves at the back of the queue, even as we gnash our teeth at the wanton failings of government of the past 10 years.

What happens to those infected older people left at home alone to survive or die? NHS England’s guarded letter to GPs claims: “We have taken urgent measures to commission a Covid-19 Home Management Service in all parts of England, to be available 24 hours a day, seven days a week.” It will “provide urgent primary care services to patients diagnosed with Covid-19 who are self-isolating in the community”. Does that sound reassuring? Not if you ask GPs. Out-of-hours services and locums are far too threadbare to care for everyone at home. Nor will they do home visits, though they can prescribe.

Dr Jonathan Leach, joint honorary secretary of the Royal College of General Practitioners and a clinical lead on the plans, says his practice, like many, is discussing how to cope with six local care homes. With mortality rates high, he says, “it’s not in patients’ interests to admit them. We need to have meaningful conversations with families about what might happen. We will tell ambulance services not to take them to hospital.”

GPs will encourage end-of-life plans, with DNR (do not resuscitate) forms. “Standard palliative care practice is to keep them comfortable.” People at home or in care homes will get four drugs to ease suffering, including morphine, a tranquiliser to stay calm, one for anti-sickness and another to dry secretions in the airways to help breathing. “We will give out this ‘just in case’ medicine, as in end-of-life care, to put in the bathroom cupboard for when it’s needed.”

“We’re not there yet,” he says, and so far there’s no official guidance. For everyone – all of us – it’s better to know what lies ahead, look it squarely in the eye and understand that when the epidemic strikes hard, there are few good alternatives.

Later will come the political post-mortem: who took what advice, and was there political pressure? Did the government get the science right? The conflict between the shut-down-and-isolate experts and the delay-quarantine-for-herd-immunity experts perplexes the rest of us.

My inbox is full of serious scientists taking issue with the government, but I can’t judge who’s right. Trust in the chief medical officer within the NHS is high. But the government takes a high political risk in diverging from other countries’ vigorous responses when every popular instinct calls for closing schools and mass testing. The NHS manager I spoke to fears that “blitz spirit” early on will soon give way to an outraged, “But that’s my grandma!”

Meanwhile, he prepares for 20% of his staff to be off sick. Hoteliers call him, eagerly offering their deserted rooms. He tells them they will be used later for convalescents, but could they now send over their cleaners, receptionists and cooks to train up for hospital jobs. He’s retraining surgeons to work under respiratory consultants. He ordered ventilators before NHS England banned it and wonders if they will be requisitioned for elsewhere when they arrive.

Asking staff their plans for when schools close, “grandparents” is often the answer, so he encourages nurses to share childcare. He will hire students from shut-down universities to clean the hospital from top to bottom, wiping every rail every two hours, non-stop. “Standing on a burning platform,” he says, “the NHS is finding out what it needn’t do.” Half his outpatients can be treated by phone and 20% of A&E admissions were needless, while centralised NHS procurement will be a lasting bonus. “There’ll be no going back.”

How about the money? He laughs: like so many, he starts at tens of millions in debt. Gleefully, he obeys the chancellor’s “Whatever it takes”. He pulled the plug on his finance team’s scratching for “cost improvements” for next year’s budget. “Money doesn’t worry me.”

What does worry him is the law. What protections will there be for the mortal decisions he makes? “Families will be within their rights to call us to inquests.” He and every other NHS official needs legal protection, for medics working beyond their skills. But, above all, they need urgent legal immunity for the dreadful decisions they alone must make.

• Polly Toynbee is a Guardian columnist