London is in Tier 4, which has the strictest restrictions, due to a severe rise in cases of the coronavirus over the past few weeks.
In the run up to New Year's Eve, healthcare workers begged people to stay home and follow the rules in an attempt to slow the spread of the virus and to stop hospitals becoming overwhelmed.
The Metropolitan Police also urged people to stay home, with Commander Paul Brogden, saying: "We are still dealing with the stark reality of fighting a deadly virus.
"The public are all too aware that tier 4 restrictions have been put in place to reduce the spread of the virus and to protect the NHS. I would urge everyone to exercise caution, listen to government advice and celebrate the new year in the comfort of their own homes, not the homes of family and friends."
However, some people decided to ignore the warning and celebrate the New Year with illegal parties.
Cops in Barking and Dagenham said they shut down an event with around 70 to 100 people in attendance.
Police found 1,000 bottles of booze at the event and seized sound equipment.
Barking and Dagenham Police tweeted: "Enquiries will be ongoing at venue re organiser & post incident. Working with partners & local residents & cctv to review.
"By attending an Unlicensed Event you put yourself, others & your families & friends at risk. That then has consequences for those in the frontline."
And that wasn't even the only gathering Barking and Dagenham Police shut down - they also gave an organiser a £10,000 after finding 60 people at an illegal get together.
In a tweet the force wrote: "We take the lives of all those within our communities seriously.
"We only intend to protect our communities & operate with Covid Tier 4 Legal Guidelines. Please help us to help you, Stay Home, Stay Safe this NYE."
Elsewhere, in the capital, a party near the Royal Docks was also shut down.
With Newham Police tweeting: "A large unlicensed music event has been shut down by officers tonight in Royal Docks.
"Arrests made and considerations being given for a £10,000 fine for breaches of Covid-19 legislation."
Alongside the illegal parties, anti-lockdown protesters also gathered in the capital.
Officers with speakerphones urged those in attendance to 'go home'.