I suppose the question could be; did the Queen propose to legislate/tell almost everyone in the UK they were not allowed to drink the left over port?
Although there is no covid law banning alcohol, the simple answer to your question is “Yes”.
Boris does not have the authority to make laws; that power rests with the Queen. Therefore she is the ultimate source of the covid laws. She signed the papers that introduced the law.
So it would be a case of her law, her staff.
Whether we agree or not on the importance of the party or not, in the end the PM accepted he broke the law and paid his fine. Would any other PM have been allowed to continue after doing so?
It would depend on the seriousness of the crime. If it warranted a prison sentence or involved fraud of some sort then I’d fully back calls for him to resign.
As it is, he paid an FPN, which others have explained means he has not been found guilty of any crime.
We also don’t know what advice was given to Cabinet Office staff (and the PM) by the building H&S lead about any covid working practices within Number 10 and the Cabinet Office.
It may well be that the official advice given to staff and the PM was incorrect.
We also don’t know why the line managers of the who also got FPNs hadn’t clamped down on their staff’s behaviours if the H&S lead had issued instructions around work bubbles.
There are a lot of unanswered questions about responsibility and guidance which means I am loath to start judging people.