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, with the dodgy graph presented to us on Halloween, one of the ‘central’ scenarios shown at the press conference suggested 4000 deaths a day or more by mid-December, based on a piece of modelling which was several weeks out of date and whose predictions were already wide of the mark.

It is perfectly credible that there is a new, more transmissible variant of the virus – viruses, do, after all, mutate all the time and the most obvious way that a variant will gain an advantage is to become more transmissible.