In summary

We now know that from the start, May 2020, Johnson attended parties in Downing Street, including his own birthday.

And this is how his defence developed:

There were no parties

I was shocked that there were parties

Any parties complied with the rules

Nobody told me parties were against the rules

I was surprised by cake

Let’s wait for Sue Gray

Let’s wait for the Met

Even if fined, I won’t resign

So, the summary of the summary:

"Any parties complied with the rules", a statement made to the House of Commons in December 2021, is a lie. Any Member of the House that knowingly lies at the Dispatch Box has to resign.