When your closest friends call around to tell you it's time to leave, you are really out of options, but Johnson couldn't even grasp this.
Having survived a no-confidence vote only recently, another no-confidence vote against Johnson couldn't be held for another 11 months. Party members would have had to change the rules and the 1922 Committee, a small but influential group of Conservative lawmakers, was prepared to do so as early as Monday.
This machination beginning to roll appears to have tipped Johnson into announcing his departure, rather than have it announced for him only days later. His stated intention to vacate Downing St in September was one last, desperate act of bravado.
One sorry lesson from Johnson's stop-frame political demise is that the mechanisms built up over centuries to preserve the integrity and authority of the UK Prime Minister's office proved too sturdy a perch for a popularist careerist with no respect for anything but his ego.
That, and Johnson was the worst kind of liar, a callous and dumb one who told untruths that were not only unnecessary but immediately obvious.