Image copyright Getty Images Image caption Earl of Derby, Walter Long and the Duke of Devonshire attending the first meeting of the Privy Council of King George V

This past week has seen a bit of concern about Jeremy Corbyn's views on monarchy: was the avowed republican wrong to stay quiet during a rendition of "God Save the Queen"? There has also been a bit of a question about whether the new Labour leader should have accepted the normal invitation to leaders of the opposition to join the Privy Council, too.

He has agreed to join this body - officially, the sovereign's corps of advisers. Membership allows Mr Corbyn access to useful briefings to Privy Council members. But there's an interesting anecdote which appeared in an early draft of a memoir by David Laws, a former cabinet minister, which bears upon this question.

Would-be members, when inducted to the council, queue up for ennoblement in a particular order set by the palace - an order of precedence fixed in an arcane and seemingly incomprehensible pattern. Mr Laws reported, in the draft, that he was unsurprised to be near the back. Mr Laws was, back then, chief secretary to the treasury - not even the top minister in his own department.

So he was baffled at finding himself near to Liam Fox, then the defence secretary. Mr Fox, after all, held a post which is much grander and older. Out of curiosity, the two men inquired how the order was drawn up. An official told them they were at the rear because of their Roman Catholicism. There is a ranking of the religions - and it puts Catholics and Muslims near the back.

Image copyright Getty Images Image caption A box containing a Privy Council dress including a cocked hat with an Ostrich feather trim from 1905, displayed in a box in the archive room at Henry Poole & Co on Savile Row

Officials' secret acts

A very modest act of discrimination (even one against Catholics like me) is not a top-tier national issue: it is, after all, only a slight against people who have made it to the Privy Council. It is also unsurprising that England's state religion has a special place in an ancient state ceremony.

But I was a little surprised to learn that the order of precedence distinguishes so carefully between different sorts of non-Anglican. And this little episode is of interest. It is still an act of discrimination. And if you are a secularist or republican, this sort of thing might be the very reason why.

Image copyright Getty Images Image caption Former cabinet minister Sir Alan Duncan wore his Privy Council uniform at Lady Thatcher's funeral in 2013

For my part, I cannot see any public interest in my keeping this episode hidden from you. That is why I find it utterly bizarre that the Cabinet Office asked Mr Laws to remove it from his memoir. Sue Gray, who is the director general for the propriety and ethics team, instructed him to take it out (I've written about her before).

Before publication, he had to send a copy of the text to her: the ministerial code observes that "former Ministers intending to publish their memoirs are required to submit the draft manuscript in good time before publication to the Cabinet Secretary and to conform to the principles set out in the Radcliffe report of 1976".

Mr Laws could have resisted the request, but that would have been a breach of the ministerial code. The real question is why Ms Gray asked him to remove that particular section of the book. What, then, is this Radcliffe Report?

What they keep out of gaze

The Radcliffe report was written in the wake of the posthumous publication of Richard Crossman's diaries in January 1975, which included unredacted discussion of cabinet meetings. The report, published shortly afterwards, took the view that there were a few categories of information that should be restricted in ex-ministers' diaries and memoirs.

There are parts of this rulebook that are understandable: the books are checked to make sure ministers do not reveal anything that "contravenes the requirements of national security operative at the time of his proposed publication" nor anything that would be "injurious to this country's relations with other nations".

Parts are less defensible: "ministers should refrain from publishing information destructive of the confidential relationships of ministers with each other, and of ministers with officials".

Image copyright Getty Images Image caption The publication of Richard Crossman's diaries in 1975, which included details of cabinet meetings, triggered the current system of vetting ministerial diaries

In effect, it says that if a retired minister must reveal they think another minister has been a fool, they should keep that a secret for 15 years. And if they must reveal that they think a permanent secretary is a fool, they should wait until the alleged fool has chosen to retire.

But nowhere in the Radcliffe guidance, as reproduced in the civil service handbook, is there anything that would let the Cabinet Office keep the Privy Council anecdote a secret. How can this redaction possibly be justified? I've asked the Cabinet Office to explain - and received a refusal to comment. The memoir process, they say, is confidential. Mr Laws has declined to comment. But a former official familiar with the chain of events told me that it happened because they are "paranoid about the palace".

You might think this minor, but there is a bigger, more important point. The Cabinet Office recently got responsibility for policy around the Freedom of Information Act. This week, it got record management policy, too.

Taken together, these policy areas make the Cabinet Office into the "Your Right to Know" department - and it has a culture of extreme secrecy. It does not hesitate to cover things up - even when it comes to the order in which people form a queue.