When Boris Johnson unveiled England’s roadmap out of lockdown, he said every step the country took would be “cautious but irreversible”.
The prime minister said, all going well, the government would end all restrictions on June 21 – a date newspapers dubbed “freedom day”.
And with the highly successful vaccine rollout and the UK recording not one single coronavirus death on Tuesday, hopes are high that the government will not be knocked off course.
But that was all before the highly transmissible Indian strain, renamed as the Delta variant by the World Health Organisation, had taken hold.
Now, scientists are warning the UK could be in the early stages of a third wave of Covid.
Here is everything you need to know.
When will we know for sure if lockdown will end on June 21?
Ministers are due to meet and review data relating to Covid and the spread of the Delta variant on June 14.
Johnson and health secretary Matt Hancock have said on this date they will know enough about whether it is safe to press ahead with the ending of all restrictions.
This is known as step four of the unlocking plan. It relates to the removal of social contact limits and the opening of nightclubs and large events.
How will ministers decide what to do?
The government has four key tests it says must be met before they push ahead with any easing of restrictions.
They are:
Is the vaccine programme on course?
Does evidence show vaccines are reducing hospital admissions and deaths in those vaccinated?
Do infection rates risk a surge in hospital admissions which would put unsustainable pressure on the NHS?
Are the risks fundamentally changed by new variants of concern?
What have scientists said?
On Friday, scientists advising the government confirmed that the coronavirus R rate in England has risen slightly and is no longer below 1.
If R is above 1, that means the pandemic is growing.
But, ministers have always expected R would rise, their greater concern is about hospitalisations and the impact of the vaccines.
Scientists are divided over what the data gathered do far can tell us.
On Monday, the UK reported more than 3,000 new Covid infections for a sixth day in a row, with many fearing the Delta variant is driving this.
Before this, the UK had not hit above that number since April 12.
Ravi Gupta, of the University of Cambridge, however, has said although new cases were “relatively low” the Delta variant was fuelling “exponential growth”.
The Sage expert added that he believed the UK is in the early stages of a third wave and called for the June 21 unlocking to be delayed.
Neil Ferguson, of Imperial College London, said the reopening of society is now “in the balance”.
And what about ministers?
Vaccines minister Nadhim Zahawi said on Sunday that “very few” of those in hospital with the virus have had both doses of a vaccine, however.
Environment secretary George Eustice was asked about a possible delay to the June 21 end-date and said ministers did not “rule anything out”.
Johnson, who has reportedly been urged to “get on with” unlocking by senior Tories, said last week that he had seen nothing yet which would mean unlocking would be scrapped.
But he did sound a note of caution about rushing out of restrictions, however, adding: “Now, as I’ve said many times, I don’t see anything currently in the data to suggest we have to deviate from the roadmap but we may need to wait.”