But it seems the fifth test – of being confident that any changes do not risk another peak – presents the biggest challenge, one that Mr Johnson is acutely aware of.
To avoid more exponential growth of the virus in the UK, the rate of infection – or ‘R’ value – must be kept below one.
That means each person who catches the virus infects fewer than one person.
We know the R value for the whole of the UK is currently less than one, but on Thursday the Prime Minister and his advisors could not put an exact number on the rate of transmission.
Despite more than 500,000 people having been tested for coronavirus in the UK, it is still thought likely to be another 18 months before a vaccine against the virus is developed.
Another hurdle the Government faces is a lack of quality antibody tests that can prove whether a person has had the virus and therefore built up possible immunity.
This, combined with its strategy for mass contact tracing – which has been disputed by scientists, who say the UK will need to recruit up to five times more people than the 18,000 originally planned – shows there is a long way to go before the UK could effectively and confidently handle a second peak.
However, on Tuesday this wording was changed to say the aim was to avoid a second peak “that overwhelms the NHS” – making it easier for ministers to say the test has been met. This has come alongside increasing signs that Boris Johnson is preparing to refine restrictions within days.
On Thursday, Mr Johnson said the Government’s “phase two” of coronavirus response would be announced next week, suggesting the first of the lockdown measures could be lifted soon.