His defense was that he went to the garden as it was an extension of the office and assumed that it was a "work event". Adding that in hindsight, he should have sent the people back inside. That's a rather poor take to be honest and the pitchforks are certainly out now.
When asked if he was going to resign during PMQs, Johnson says that "we should not pre-empt the outcome of the inquiry". Yikes.
There's going to be a lot of pressure for him to step down and there might even be a private call for a leadership challenge in the Tory party. I don't see this having much political impact on the pound but it's good to stay abreast of the news.