Tony Blair quit after a handful of minnow PPSs and junior ministers applied a bit of pressure.
His successor is still prime minister after five cabinet resignations, two junior ministerial resignations and a genuine backbench mutiny.
Does this make Gordon Brown – in his ability to evade political homicide – the Grigory Efimovich Rasputin of 21st century London?
Consider the facts: Rasputin was given potassium cyanide crystals in pastries and wine. Then he was shot in the stomach. Later, shot in the back of the head. Then kicked in the head and beaten with dumb-bells. His murderers succeeded only after tying him up in rope and cloth and dumping him in a river.