Health secretary Matt Hancock has warned that ministers will fail to get the new strain of coronavirus under control unless the public take personal responsibility for preventing its spread.
He called on all those in the new Tier 4 areas in England to act as if they currently have Covid-19, as he warned cases had “absolutely rocketed” in the last few weeks.
He was speaking as footage emerged showing large queues in London train stations as thousands attempted to flee the capital before tough new restrictions, including on travel, came into force.
But doctors’ leaders accused Mr Hancock and other ministers of failing to follow the science last week as they clung to plans to allow families across the UK to meet for almost a week over the festive period.
On Saturday Boris Johnson dramatically cancelled the Christmas plans of millions, just days after he said that to do so would be “inhuman”.
The prime minister ordered a strict new lockdown in vast swathes of southeast England and London, issuing “stay at home” orders and banning gatherings in areas in the new tier 4.
Across the rest of England, he also scrapped a planned five-day relaxation of the rules between 23 and 27 December.
Households will be allowed to form Christmas “bubbles” only for a single day on 25 December.
Within hours both Scotland and Wales announced they had adopted the same policy.
Wales also announced it was entering an immediate lockdown, amid fears of rising case numbers there.
Shadow foreign secretary Lisa Nandy said she was “angry” that ministers had spent days dismissing concerns that Christmas plans would have to be changed.
“Over and over again we have seen the same pattern, a prime minister who rejects the evidence … and ends up having to change his mind at the eleventh hour… We cannot continue like this.”
