Police found 29 people at a converted shisha bar on a London industrial estate in a breach of Covid-19 lockdown rules.
Footage of the unit in Southall, west London, showed one man trying to run away when officers arrived.
The owner faces a fine for the breach after police in the capital warned they will crack down on unauthorised gatherings and the government stepped up its efforts to persuade people to stay at home and obey the lockdown.
The discovery is the latest breach of rules involving shisha cafes. Police found about 50 people smoking shisha pipes and watching football at a café in Wembley, north-west London, in December.
Britain’s Covid-19 regulations ban mixing between people from different households, other than in limited circumstances.
The capital’s police said they had found a bar open and serving customers and 14 people gathering for a car meeting over the past week.
“There can be no doubt that by staying at home, you are helping to save lives by minimising the transmission,” said Deputy Assistant Commissioner Matt Twist.
“Astonishingly there remains a small minority who are ignorant to these risks and who continue to make reckless and dangerous decisions.
“The [National Health Service] is under significant strain and the actions by some people to hold parties or large gatherings is frankly shameful.
“In those cases where people have made it clear they are prepared to put lives in danger by holding large gatherings, we will move swiftly to enforcement.”
A new government advertisement warns people “don’t let a coffee cost a life” as it tries to persuade people to stay at home, and Prime Minister Boris Johnson urged the public to obey the national lockdown as coronavirus deaths continued to rise steeply.
"Please really think twice before leaving the house this weekend and only do so if it's absolutely necessary," Mr Johnson said in a video posted on Twitter.
The latest government figures showed a 50 per cent rise in weekly deaths, taking the total toll to more than 86,000, the highest in Europe.
Meanwhile, the number of positive cases has reached nearly 3.3 million, but new infections fell 7 per cent in the last week.
Officials believe the declining case rates are due to the stringent lockdown, but concede there will be a time lag before hospital admissions and deaths also drop.
In a bid to inoculate the most vulnerable against Covid-19, Britain is rapidly rolling out its programme.
It has so far issued more than three million doses as part of a drive to vaccinate the four groups of most vulnerable people by the middle of next month, and every adult by the autumn.
"Jab by jab, we will win this fight against Covid," Mr Johnson said, adding that this "extraordinary national effort is only going to accelerate."
