Documents are not given a security classification by a government (or indeed by any other person or organisation) solely because they contain information known only to them.
Sometimes the secret is that politicians or spies are interested in, talking about, thinking of doing something about, the subject. That is what they do not want you to know.
And sometimes it is just cover for their obtuseness.
Or rudeness. After all, that is why doctors used to argue against the idea that we should have the right to see our own medical notes – all those Normal For Norfolk remarks.
