He's had years of sex scandals and disgusting comments, but has been Teflon. What seemed to bring him down was the revelation that his office was having parties during 2020 lockdowns, lockdowns that were, unlike what went on in the US, enforced, and where a lot of people sacrificed (and a number of people died). They tried to tough through this, but a poor economy and increasing isolation from the rest of the world due to Brexit did not help. They began losing byelection after byelection (special elections), including some that the party had won by massive margins before that point.