I regard it as meaning the denial or interdiction of information by decree (usually Order in Council, occasionally by Statute) when applied by government. The term can be stretched to include deliberate omission or distortion of "news" by private or corporate pressure, or the threat of civil damages, but I would like to look at censorship by government.
In my view this is justifiable in two categories only, and they should be drawn as narrowly as possible.
First, the vexatious heading of "national security". Most people would accept that technical service information - the operational charts of ocean-going submarines; codes and cyphers; key sequences in electronic counter-measure, for example - are properly kept secret. And in the intelligence field the authorities have a duty to protect as best they can the lives (and thus usually the identities) of their agents.
The second area in which a measure of censorship by government is legitimate (but where, I am sorry to say, it is often abused) is that classified as "commercial confidentiality". Plainly, where an investor with prior knowledge could make a fast profit - ministerial procurement contracts, referrals to the Monopolies and Mergers Commission - the authorities have an equitable duty to avoid premature disclosure.
There are three other categories where governments do practise, or at least attempt to apply, censorship. In my view they do so quite wrongly and often under the pretence that one or both of the two "primary" considerations apply. These are administrative convenience, public reputation of ministers or officials, and personal embarrassment.
Most MPs are slack and incompetent, if not actually venal, in their operation of the procedure for parliamentary questions. They draft usually on the basis of getting a headline that will, if noticed by their constituents, indicate "activity". Some table, or get their researchers to draft, hundreds. Some occasionally perk up a bit and take (extra) money for so doing.
Very few MPs - Tam Dalyell is the most effective and persistent, but Nicholas Budgen and Richard Shepherd are also "dangerous" - have mastered the technique of repeated interrogation: how to use last week's ministerial answer as the building block for next week's question. But if you have worked in a minister's outer office you will know the flap that precedes "First for Questions". There is an apprehension not just that the minister will fluff his answer, but that something might be given away that will lead to more work; establishment, or erosion, of "precedent"; even a reproachful note from his permanent (or, still worse, the cabinet) secretary. All because of this one critical pitfall: a minister must not lie to the House of Commons. If he does, he's out. The same day.
As a result, every Question Time is a potential bout of arm-wrestling between the established order and those who have the capability, though it seems very seldom the inclination, to discover the truth. I always found it strange that MPs did so little to press their advantage here. I never saw officials actually repress information, although sometimes they would withhold it (passim Sir Robin Butler, "Truth can be no more than half the picture"). But here no reform is needed, except to the intelligence and tenacity of those who are entitled to put the questions.
The fourth category, which as a historian I have always found particularly irritating (and which, of course, often overlaps with that of administrative convenience), is the protection of reputations. As we know, this can be extended from the reputation of a deceased functionary into a general susceptibility to the feelings of relatives, and even surviving offspring.
The arguments are well-rehearsed. They are deployed to justify the 30- year rule, which is too often extended to 50 years, sometimes even to the total excision and destruction of documents. Freedom of discussion and the quality of official advice would be inhibited if the participants thought that their fallibility might, with hindsight, be prematurely (sic) revealed.
This is completely bogus. The public are not allowed to know the truth about Cabinet discussion of peace terms with Hitler; or the contents of Rudolf Hess's brief which he brought on his mission in 1941; or the wartime antics and financial speculations of the Duke of Windsor; or the full degree of pressure applied by the Americans to sterling over Suez; or the text of the consultations during the Cuban missile crisis. None of this has anything to do with personal reputations. It is far more a kind of general "not-in-the-public interest" factor.
You might ask, why not? To which the only possible answers are (a) "because not"; and (b) "because it might lower the esteem in which you held your elders and betters". Unbelievably, (b) is also deployed as a serious argument to justify the suppression of reportage (only disreputable reportage, of course) concerning the "private lives" of politicians, members of the Royal Family, and, it sometimes seems, even the more prominent alumni of caf society.
These are people who spend a large part of their own time writing personal press releases, searching for photo opportunities, paying agencies to contrive or fabricate favourable "publicity". On what possible basis can they claim that they should enjoy some kind of immunity from comment if the technique goes wrong?
The last category, where I believe the arguments are more finely balanced, but which I approach with diffidence as I have strong feelings about it but no expertise, is pornography.
I dislike the material intensely. Some of the most disagreeable intellectual experiences that I have had to endure as an MP involved the display of suspiciously "lifelike" videos seized by the police (which they were subsequently forced by the courts to release) showing appalling violence and sexual abuse against children and women.
Common sense tells me that these films are an encouragement to commit crimes of a particularly cruel and degrading kind, and that both their manufacture and their distribution should be visited by heavy penalties.
But at the same time I recognise that many of the general convictions that I hold in rejecting most other forms of censorship may make this standpoint difficult to sustain in logic.
This article is taken from the new issue of `Index on Censorship', published on Monday, which examines the state of free speech in Britain today. Copies available from bookshops, or telephone 0171-278 2313.