Exit strategy: how Boris Johnson may be forced to resign

Prime minister's next steps hard to call due to unreliability of his logic and desire to act in interest of Tory party

By any normal metric it is fair to say Boris Johnson is doomed, given the scale of ministerial resignations and the number of backbench MPs publicly withdrawing their support. While Johnson has often defied normal political rules, it does seem a matter of when he is ousted from No 10 rather than if. But how? Here are some scenarios.