The rumours began a week after Boris Johnson began self-isolating in the flat above No 11 Downing Street. The story, spread by the prime minister and his aides, had thus far been reassuring.
Yes, he had Covid-19. But the symptoms were nothing to worry about. Mild even. And at a time when deaths from the pandemic were continuing to climb, Johnson had a firm grip on the crisis and the machinery of power.
All of this changed on Thursday 2 April. At the lunchtime briefing for lobby correspondents, Downing Street stuck to this soothing script. The prime minister continued to have a temperature.
