Police have been left “in absolute shock” after finding 25 adults and children having a “massive party”.
Everyone was dispersed and the hosts “dealt with” after social-distancing rules were breached in Derby.
It comes after Derbyshire Police was criticised earlier in the week when it released drone footage of people in pairs rambling in the Peak District.
However, the force has said it is merely applying the legislation the government has passed.
The force said: “It is clear people are still having complete disregard for the Government advice and rules.”
Some people were supportive of the police’s action, while others criticised them, in online comments.
However, many more were concerned about the food on offer in the buffet.
Previously, former justice secretary David Gauke had described police drone footage of walkers being released as “badly misjudged” and pointed out the people in the footage were maintaining a social distance.
However, the government then clarified its advice over daily exercise, saying people should “stay local” and not travel unnecessarily for exercise.
Privacy campaigners Big Brother Watch said filming members of the public and publishing footage online was “sinister, let alone counter-productive”.
Supt Steve Pont, of Derbyshire Police, told the BBC’s Today programme: “We wanted to reinforce the message of stay home and a number of people aren’t staying home, they’re finding excuses or loopholes – and we just wanted to illustrate that this is the wrong thing to do.”