Today's published Commons order papers contain a question to be answered by a minister later this week. The Guardian is prevented from identifying the MP who has asked the question, what the question is, which minister might answer it, or where the question is to be found.
The Guardian is also forbidden from telling its readers why the paper is prevented - for the first time in memory - from reporting parliament. Legal obstacles, which cannot be identified, involve proceedings, which cannot be mentioned, on behalf of a client who must remain secret.
The only fact the Guardian can report is that the case involves the London solicitors Carter-Ruck, who specialise in suing the media for clients, who include individuals or global corporations...
The right to report parliament was the subject of many struggles in the 18th century, with the MP and journalist John Wilkes fighting every authority - up to the king - over the right to keep the public informed. After Wilkes's battle, wrote the historian Robert Hargreaves, "it gradually became accepted that the public had a constitutional right to know what their elected representatives were up to".
(Thanks to Andy and everyone else who suggested this!)