Harsh new coronavirus restrictions over Christmas time are expected to “flatten the curve”, a senor Government adviser has said, but hinted at the possibility of further measures in January.

Professor Neil Ferguson, a member of the Government’s New and Emerging Respiratory Virus Threats advisory group (NervTag), warned the new mutant strain which has infected swathes of people across south-eastern England, London and beyond, was “everywhere now”, but said he expected new measures to help control it.

Prof Ferguson told the committee on Wednesday: “Schools are now shut, we are in a near-lockdown situation across the country, contact rates are lower over Christmas.

“I expect, though I hesitate to make any sort of predictions, we will see a flattening of the curve in the next two weeks.

“We will see at least a slowing of growth.”

He added: “Exactly what we will see is almost impossible to predict.

“If we start to see a significant decline over the next two weeks in case numbers overall and case numbers of this variant, I would not say we were in a great position … but it offers a little more optimism that maybe we can keep on top of this.

“If we see case numbers increase, which is not my expectation, we will be in a very difficult position.”

Prof Ferguson said the “critical question” was what happens in January, “and the extent we want to make public health measures more uniform across the country if the new variant is everywhere”.

London and parts of southern and eastern England were rushed into the new Tier 4 lockdown regime at the weekend, effectively taking a scythe to Christmas plans and imposing measures similar to the previous national lockdowns amid the rise of the new coronavirus mutant strain.

Scotland and Northern Ireland have already announced new lockdowns from Boxing Day, while Wales’s tough restrictions will only be eased for Christmas Day before being re-imposed.

Prof Ferguson said there was merit in restricting travel across the UK, despite the virus’ apparent omnipresence.

He told the committee: “To some extent, every little helps.

“Christmas is associated with a lot of travel around the country, so restricting that does help you prevent the situation of suddenly increasing the frequency of the virus.

“It’s everywhere now, we can’t stop it, but it’s still beneficial to not let it jump up dramatically because we are letting people move around.”

The committee heard it was “likely” the new strain started from one person in Kent, but have been caused by a random mutation.

Asked if a lax attitude towards lockdown measures could have caused the mutant strain to spread, Prof Ferguson said corroboration of other data suggested otherwise.

He said: “There was nothing special about what was going on in Kent and the south of England during lockdown compared with other areas of the country.

“We saw the non-variant decline in a particular week and place, whilst the variant increased in the same week and place in the same population.”

Latest official figures showed a further 691 people had died within 28 days of testing positive for Covid-19 as of Tuesday and there had been another 36,804 lab-confirmed cases of coronavirus in the UK.