Last April, after the resignation of the then culture secretary Maria Miller, who'd got herself into some expenses trouble, I proposed a five-point test for MPs in trouble. In a spirit of helpfulness, I''m republishing them today.
1. Always apply the Private Eye test: would you be happy if what you're about to do appeared in Private Eye? If the answer is No, don't do it. Simples.
2. If allegations are made against you and it's a fair cop, say so, explain if you must, then quit. Quickly.
3. If the allegations aren't true, say so, resign if you have a front-bench job, and say you hope to be back after you've been cleared.
4. If you're a minister and your department is responsible for an almighty cock-up, admit it, apologise, and resign. You enjoy the perks when the going is good; this is the price you pay. Does anyone still remember Lord Carrington, who resigned as foreign secretary in 1982 after Argentina invaded the Falklands? It was hardly his fault, but he took responsibility.
5. And one last piece of advice for prime ministers: if a member of your Cabinet is in serious trouble, don't think you can tough it out. You can't, and you'll be damaged goods when you lose.
The late, great political columnist Alan Watkins, from whom I learned everything I needed to know about politics, first as an avid reader of his columns and then as a colleague, used to say: "Politics is a rough old trade." And so it is. No politician should ever even dream of complaining "It's not fair."