How sure can we be that the Tier 4 lockdown will work?

How certain should we be of the government’s claim that the new variant of SARS-CoV-2 is 70 per cent more transmissible than the previous common strain falls apart? I ask not because I have any information that would contradict the Prime Minister, but because it has become a repetitive feature of this crisis: that the piece of science which leads the government into a sudden change in policy ends up looking a little flaky. It happened with Professor Ferguson’s famous prediction of 240,000 deaths unless the government introduced the first lockdown – Imperial published similar figures for Sweden which were later shown to vastly overstate deaths, throwing serious doubt upon its model. It happened, too,