It's true that sometimes They know things that we don't. I didn't know that Chinese officials talking to American officials feel free to brief against North Korea - and I was a bit relieved to discover that they do. It reassures me that the Chinese are rational.
But a lot of the time They don't know any more than we do - and sometimes less. This is true both for diplomats and spies. They both move in rarified circles and it would call into question their salaries and their status if they conceded that, actually, you can generally find out more by reading the newspapers and Googling. Or by reading books.
But the moment something becomes Secret, it acquires an authority which makes it worth leaking. It then becomes headline news.
Before the UKs last General Election no one ever claimed that David Cameron and George Osborne were in the rocket science class when it came to understanding the fiscal and monetary measures needed to keep UK plc afloat. Gordon Brown claimed rocket scientist status for himself and the press had awarded the title to Vince Cable. When it came to forming a Coalition cabinet, there was a general feeling that though it had to be Osborne at the Treasury, it ought to have been Vince.
So it's no surprise that Mervyn King, Governor of the Bank of England, should have been unimpressed by Cameron-Osborne. It may be more surprising that he shared his assessment with the American ambassador, but then it is a diplomat's job to get people talking and King was not saying anything terribly controversial.
Once again I feel relieved: just like the Chinese officials, the Governor of the Bank of England seems to have got his head screwed on.
Whenever I am in danger of being overawed by the wisdom of those whose emails are marked Secret, I remind myself of how, at the time of the Kosovo conflict, NATO forces came to bomb a Chinese mission in Belgrade thinking it was a Serbian military or police installation. They hadn't consulted an up to date Guide Book.