But the Public Health England research he cited was six months old and carried out before the vast majority of the public had been vaccinated against Covid.

It also involved only those who had been alerted by NHS Test and Trace as close contacts of positive cases.

The Prime Minister implied it covered the NHS Covid app, which had not been rolled out at the time. The app tends to be less reliable at identifying close contacts than Test and Trace and can ‚ping‘ people through walls.