The Rules
At the time of the party, the COVID restrictions clearly stated that only 30 people were allowed to attend indoor gatherings. Of course, these rules are constantly changing, so it is difficult sometimes to keep track of what it allowed.
Hand Out Fines
Legally, police officers are allowed to hand out £10,000 to anyone who breaches COVID restrictions, including organizing an illegal gathering. Furthermore, they are allowed to hand out these fines without an appeals process.