But Health Secretary Matt Hancock has signalled to MPs that the review will look at "decoupling" areas in a move which should quell a brewing Conservative backbench rebellion.
The British government on Monday cited a rise in new infections, which it said may be partly linked to the new variant, as it moved its capital city and many other areas into the highest tier of COVID-19 restrictions.
The four nations of the United Kingdom will relax restrictions to allow up to three households to meet at home for five days over Christmas.
"But what I do know is that the Public Health England colleagues were in close contact with Matt Hancock and have been from the start of concern about this and so he's been informed by colleagues there".
Will you alter your Christmas plans this year after the rise in coronavirus cases?
"The new mutation is in the protein (Spike) of the SARS-CoV2 virus that numerous vaccines were created to target", Dr.
Professor Stephen Reicher, of the University of St Andrews, said: "Right now we are heading towards disaster".
He called on the government to scrap the Serco contract and instead increase funds to public health teams that carry out more efficient contact tracing while receiving a combined total of just £785 million.
The chief executive of the NHS Confederation, Danny Mortimer, questioned whether "these rules will be enough to protect the population in the short term".
He told the BBC: "Let's not be hysterical". People are told to minimize travelling within or to the area, and Hancock said people shouldn't take trips into central London to do Christmas shopping. We want people to take it very seriously and go no further than they have to'.
The main difference between the top two tiers is that bars and restaurants, which can stay open under certain conditions in tier two, must close their doors in tier three and can only operate takeaway services.
It means 14,000 pubs and food venues must shut except for takeaways and deliveries. It's not going from a Tier 3 to Tier 0.
Hancock acknowledged the measures would be a "blow" to people and businesses as he addressed a Downing Street press conference.
The genetic changes to the virus' spike proteins would not reduce the effectiveness of a coronavirus vaccine as most produce a range of antibodies that would make it hard for the virus to evade all at once.
He said there was "nothing to suggest this is more likely to cause serious disease" and that it was "highly unlikely" it would "fail to respond to a vaccine".
More than 20,000 cases of COVID-19 have been reported in London in a week.
However, retail and schools will remain open.