The vast majority of people are following the lockdown rules despite images showing some people flouting them, Professor Chris Whitty has said.
Speaking to the Science and Technology Committee, England’s chief medical officer told MPs on Tuesday that photos depicting widespread breaking of the laws were “not the reality on the ground”.
“The great majority of people both intend to stick to the rules and do stick to the rules to a remarkable degree,” he said.
“Were that not the case, we would be in a massively worse place than we are at the moment.
“My expectation is R would have shot right up if people had not massively reduced the number of people they have contact with, really stuck to all the things we need to do in terms of individual actions they can take – hands, face, space – and done a huge amount in businesses to try and make them COVID secure.
“Without that, we would be in a very, very difficult place compared to where we are now.”
It comes after police have been forced to break up large-scale gatherings across England in recent weeks where revellers were in breach of social distancing rules.
Huge crowds gathered in the centre of Liverpool last month the day before the city moved into Tier 3 lockdown restrictions.
Liverpool mayor said the revellers "shame our city" at a time when the region was recording one of the hospital admission rates in the UK.
Similar scenes were witnessed in Nottingham on the eve of its own Tier 3 lockdown last week, as police there dealt with scores of drunken revellers.
Watch: Chris Whitty tells MPs hospital admissions have passed first wave peak
And on Saturday night, officers in the South West were forced to break up an illegal rave in Yate, near Bristol.
Video clips and photos from the Halloween party showed revellers crammed into a warehouse without social distancing.
Despite the recent breaches, Whitty remained positive that the second lockdown could work and argued that the majority of people would follow the rules.
“If people adhere in the way that I expect they will, it'll reduce R below 1, in my view, in the great majority or all of the country,” he added.
“I wouldn't want to imply that suddenly that means that COVID is over as a problem.
“This is a long haul.”
He added: “We need to see this through winter – this doesn't mean we need to stay in these measures through winter, but we will need to be doing things that keep the rates down.”
When asked if the restrictions would be lifted on 2 December, Whitty said: “The decision as to whether to lift restrictions on 2 December is rightly a decision for ministers and Parliament.
“I think that the aim of this is to get the rates down far enough that it's a realistic possibility to move into a different state of state of play at that point in time.”
Watch: Can you catch coronavirus twice?
Coronavirus: what happened today