Police who issued a £10,000 fine to the organiser of a student party were forced to withdraw it because they could not prove the event was pre-arranged or that the guests had travelled from their homes to attend.
Officers were called to a halls of residence at the University of Lincoln on December 4 following reports that up to 100 students were breaching coronavirus rules by staging a large party.
But in an embarrassing climbdown the force has now had to withdraw the fine after admitting they did not have the evidence to prove the party had been a single event that was pre-arranged.
Chief Constable Chris Haward said further investigations had revealed that rather than one party taking place, the event had been made up of a number of individual gatherings.
Watch: Hundreds caught at illegal rave in east London as police hand out fines worth £15,600
Explaining the decision to cancel the fine, Mr Haward said: "All of the FPNs (fixed penalty notice) that we issue under the coronavirus legislation are reviewed to ensure that they are proportionate and necessary.
"It is important to ensure that due diligence is in place when considering the legal burden of proof placed on the police – in this particular case the fine of £10k was significant and likely to proceed to a court hearing. In this case we latterly discovered an evidential difficulty.
“The ticket had been issued by the attending officer in good faith but this further investigation highlighted that this was not one single pre-arranged party, it was in fact a number of people within the same accommodation building having individual parties.
“There was no evidence to show that any of those in attendance had travelled, and a large number of them would have been classed as a household as they lived in the same corridor of the building and shared various facilities.
“It was an evolving situation that led to a large number of people drinking and socialising within the accommodation at the same time."
He added: “The review of the case meant that in these particular circumstances the offence was not in fact as we had at first considered, and as such the only option open to us was to cancel the fine."
The fines were introduced in September and official figures suggest there have been more than 750 fines of £10,000 issued by police forces in England and Wales during lockdown.
But it is not clear how many have been paid in full as the fines are means tested and could also be subject to legal challenge.
Lincolnshire Police were alerted to the student gathering on the evening of December 4 when local residents claimed they could hear a "party raging" at the Viking House accommodation block opposite the main University of Lincoln campus.
One witness claimed she could see a disco light shining from inside the building and could hear lots of noise.
At the time Chief Superintendent Jon McAdam from Lincolnshire Police said: "In a situation such as this, in a time now when it's quite clear that everyone knows the rules, there was no way we could have done anything other than hand out the maximum penalty."
The decision to drop the fine infuriated some locals who had been following the case.
Helen Thompson, from Lincoln, said: "Students used to get 'sent down' from University, ie chucked out, for really bad behaviour, especially if it brought the establishment into disrepute."
When the fine was first issued the University of Lincoln said it was taking the matter “extremely seriously” and had launched an internal investigation.
The University has now said it is unable to comment on the internal investigation due to privacy reasons.
But a spokesperson said: “We encourage all of our students to follow the rules and act responsibly to help stop the spread of the virus and keep our community safe.
"We are proud of the vast majority of our students who are doing so.
Watch: Police injured breaking up 200-person party in Knightsbridge