If you are in charge of a business, or part of government, ... you need to be able to think and talk a little wildly, to test extreme positions and unlikely ideas, to speculate and joke, before you settle on a course of action. Almost all of us say things in private which we would be aghast to hear loudly quoted amongst our friends and neighbours. ... The freedom to talk in a fully relaxed way is a human need. Even if you decide not to close your traditional head office, or invade a country, or move your family to the Hebrides, you may need to consider doing so, and to talk about what would happen if you did. Without speculation there can be no good decision making: yet such is the authority and importance of government that its speculation, if revealed, can cause people to riot, foreign governments to protest, and ministers seem very foolish indeed. The ill-considered private joke becomes a deadly headline. The wild surmise becomes a plan. If we were all publicly judged on our private, intimate conversations we would dry into inner silence, and the same is true of governments.

They know it. This explains the surviving code of civil service confidentiality today. It is why advice given to Cabinet ministers about different ways they might act, and the debates in their private offices, and the negotiations inside Cabinet committees, all stay private.

Please do contact me if you spot any other material which needs supplementing or correcting.