Downing Street hosted three parties while everyone was locked down and told they couldn't visit dying relatives:
November 13 2020 Carrie/Boris flat party
December 18 2020 Downing Street party
Christmas Quiz (date unclear)
Seems that the reason this may have initially received limited press coverage is potentially due to members of the press being at the parties in question. Johnson says parties didn't take place but if they did no rules were broken. Given the rules at the time hard to see how that can possibly be true. Media appearances by members of the government are being cancelled in case they are asked about the parties.
Government have said the reports will be investigated by Cabinet Secretary Simon Case but they have refused to deny he was at one or more of the parties himself. The issue was referred to the met who have said they don't investigate crimes that took place in the past. At literally the same time they were saying that there was a court hearing taking place with a member of the public being charged with holding a party in breach of covid regulations which was allegedly held at the same time as the Downing Street party.
There's also video of them joking about how the party wasn't socially distanced and wouldn't be investigated.