Boris Johnson has stressed that “there really is such a thing as society” in a message released he is while self-isolating with Covid-19, in which he also revealed that 20,000 former NHS staff have returned to help battle the virus.

The prime minister chose to contradict his Conservative predecessor Margaret Thatcher’s endorsement of pure individualism made in 1987, when the then PM told a magazine: “There is no such thing as society.”

In his video message, Johnson said: “We are going to do it, we are going to do it together. One thing I think the coronavirus crisis has already proved is that there really is such a thing as society.”

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He thanked the doctors, nurses and other former professionals for returning to duty, as well as the 750,000 members of the public who have volunteered to aid the health service.

Johnson has continued to command the response to the Covid-19 pandemic while sealed behind closed doors in his flat above No 11 Downing Street.

In the self-shot video, the prime minister said the public appeared to be obeying the terms of the lockdown to slow the spread of the disease, saying train use was down 95% and bus use down 75%.

“Thank you to everybody who’s now coming back into the NHS in such huge numbers,” he continued. “Just this evening I can tell you we have 20,000 NHS staff coming back to the colours.

“It’s a most amazing thing. And that’s in addition to the 750,000 members of the public who have volunteered to help us get through this crisis.”

On Thursday, NHS national medical director Prof Stephen Powis said the figure of former professionals who had volunteered to come back stood at more than 15,000.

Johnson’s message came after the nation was warned by the deputy chief medical officer for England, Dr Jenny Harries, that normality may not resume for at least six months.

This does not mean a “complete lockdown” will last the entire time, she stressed, but physical distancing measures will be gradually eased as the crisis wanes and the pressure on the NHS eases.