The model, based on 13-year-old code for a long-feared influenza pandemic, assumed that the demand for intensive care units would be the same for both infections. Data from China soon showed this to be dangerously wrong, but the model was only updated when more data poured out of Italy, where intensive care was swiftly overwhelmed and deaths shot up.

It did not consider the impact of widespread rapid testing, contact tracing and isolation, which can be used in the early stages of an epidemic or in lockdown conditions to keep infections down to such an extent that when restrictions are lifted the virus should not rebound.

One moment the prime minister, Boris Johnson, was asking people with symptoms to stay home for seven days; a few days later, he had ordered a lockdown. What changed was data from Italy’s experience of the pandemic, in which more people were critically ill than anticipated, and from the NHS about its inability to cope if the same should happen in the UK.

The national media has lamented the lag in timely mortality figures due to the different ways care homes record such data. Data sharing between national and local government on medically shielded individuals and lists of volunteers has been a major talking point in cross-departmental discussions. And individual local authorities are acutely aware that they can’t afford to wait six months to be able to share data on factors affecting vulnerability between them — a typical length of time for signing a multi-organisation Information Sharing Agreement.