Though winter crises are nothing new to the NHS, this one is proving exceptionally difficult. By any measure, patients are waiting longer in A&E. The number waiting more than 12 hours for a bed once it has been decided they need to be admitted to hospital (so-called trolley waits), was up more than eightfold in December 2019 on December 2018. Performance is declining, and doing so increasingly quickly.

The headline measure of performance in A&E is the percentage of patients who are admitted, transferred or discharged within four hours. The target was introduced in 2001, the start of a golden era for the (lack of) waiting in A&E that was to last a decade. Targets of this kind have been criticised for distorting clinical priorities and creating perverse incentives for hospitals to meet the targets at all costs.

But there is a clinical justification for a target that ensures patients in A&E are treated as soon as possible, and this and other targets did contribute to the step change in NHS performance and public satisfaction. Crucially, they did not achieve this in isolation – the decade also saw record-breaking increases in NHS funding and workforce growth that went hand in hand with the targets.

The world has moved on since then, yet the four-hour standard has only been tinkered with. So the current review of the A&E target – being led by NHS England’s medical director, Steve Powis – is perfectly appropriate. The health secretary, Matt Hancock, finds himself in hot water for suggesting, before the review has reported, that the target could be scrapped. Ultimately, the value of the review’s recommendations must be judged on whether they would drive a better experience for patients – and carry the confidence of clinical staff.

Turning round the NHS supertanker takes time. The new government must take action now

What the review must not be is a clandestine attempt to improve wait times by watering down standards in A&E, in the hope the media and public will then forget the current crisis. This would be a self-defeating exercise: the Blair government introduced the target because it had little choice – by 2000 it was perfectly clear to everyone that waiting times in A&E had become unacceptable. The target and the publication of performance data was the response to these unacceptable waits and the accompanying public concern; it did not cause them.

Whatever way we measure waiting in A&E, it is clear it matters to patients. Polling shows that waiting times for treatment are at or near the top of public’s concerns about the NHS; and when asked, people strongly support the four-hour target. Over the coming years, the NHS will need to stop the decline in performance and go some way to reversing it. Clever (or not so clever) redefinitions of the target will not by themselves improve performance.

This can only be achieved by major investment in NHS capacity, which the government is now doing after a decade of underinvestment. Primarily, this means more staff so patients can be admitted safely to a hospital bed.

While investment in general practice and communities may help slow the rise in the demand NHS hospitals are facing (and help get patients out quickly when they have been admitted), the number of hospital beds in England is looking increasingly unsustainable in the light of ever-full, and overfull, wards. Twenty years on from the last national beds inquiry, we need a new review of the number of hospital beds and appropriate staffing levels to cope with rising demand.

The key staff group needed to boost hospital capacity for emergency care is nurses, so the government’s manifesto commitment to finding an extra 50,000 is welcome. But, as the 2000s also showed us, turning round the NHS supertanker takes time. The new government has five years before it faces the electorate again – it must take action now.

• Richard Murray is chief executive of the King’s Fund