Plan B involves advice to work at home and requirements to wear masks in certain scenarios.

In a recent report, the National Audit Office (NAO) said that the coronavirus pandemic exposed Britain's vulnerability to whole-system emergencies and left the British government unprepared.

The government did not act on warnings from pandemic simulations carried out prior to COVID-19 based on an influenza outbreak, said the NAO.

Gareth Davies, head of the NAO said: "This pandemic has exposed the UK's vulnerability to whole-system emergencies, where the emergency is so broad that it engages all levels of government and society. Although government had plans for a flu pandemic, it was not prepared for a pandemic like COVID-19 and did not learn important lessons from the simulation exercises it carried out."