Perhaps the nation was not as prepared as it could have been. Extract from the National Risk Register, not updated since 2017. I was searching for the parameters that trigger a State of Emergency
It is difficult to forecast the spread and impact of a new flu strain or disease until it starts
circulating. However, consequences may include:
• for pandemic flu:
o up to 50% of the UK population experiencing symptoms, potentially leading to
between 20,000 and 750,000 fatalities and high levels of absence from work.
• for emerging infectious diseases:
o several thousand people experiencing symptoms, potentially leading to up to 100
fatalities.
• disruption to essential services, particularly health and education; and
• economic disruption, including disruption to business and tourism.