Among those detained was the Palestinian writer and academic Abbas Shiblak, who had lived in Britain for many years and was well-known - to everyone but the police and the Security Services - as a moderate. Mr Shiblak was freed after two weeks of internment, followed a week later by an Iraqi student who managed to persuade officials they had got the wrong man. Displaying the traditional English dyslexia about foreign names, the Security Services had mixed him up with someone else - someone who was probably as innocent as the rest of the unfortunates.
This was confirmed in March 1991 when the then Home Secretary, Kenneth Baker, announced there would be no deportations and no trials as a result of the round-up. Indeed, Mr Baker was said to have been shocked by the flimsy, anecdotal evidence used to compile the list and later ordered an inquiry into what many observers regarded as a scandalous abuse of human rights. The Home Office recognised that some of the Iraqi students whom MI5 and Special Branch had fingered were genuine refugees.
What this demonstrates is that, when it comes to identifying terrorists in this country, relying on "intelligence" gathered by MI5 and Special Branch is about as effective as picking foreign-sounding names from the telephone directory. (Irish accents are similarly popular with the police, as the Birmingham Six discovered.) Not that the Security Services learnt much from their dismal performance in 1991. In February this year, when air strikes against Iraq once again looked imminent, they were apparently ready with another list of potential detainees - until the Government squashed the idea.
In the wake of the Omagh bombing, and the terrorist attacks on the American embassies in Kenya and Tanzania, all this is in danger of being forgotten. Last week, in an emotional speech in Northern Ireland, Tony Blair announced a package of anti-terrorist measures the centrepiece of which is the relaxation of the rules of evidence in the province. Once the new law is rushed through Parliament on Wednesday and Thursday, it will be possible to convict suspects of belonging to a proscribed organisation solely on the word of a senior police officer. This is not strictly internment but it carries the same risks, of honest mistakes and malicious identifications, which are credited with having recruited so many new members to the IRA in the 1970s. The law is aimed at the Real IRA, but there is nothing to stop it being used against members of other political organisations in future. Panic measures, hurried on to the statute books in a matter of days, remain in force for decades, available to governments of a quite different stripe from the one that originally proposed them. As a separate part of the same package, it will become an offence to conspire to commit criminal offences abroad, a measure which Liberty described last week as "a serious threat to human rights".
Conspiracy trials rarely turn on hard evidence, for the simple reason that people who intend to commit criminal acts infrequently document their intentions on paper. Convictions tend to depend on circumstantial evidence, such as membership of political organisations - not quite the same as being put on trial for your politics, but it comes close. It will even be an offence, according to some reports, to collect funds for a terrorist organisation abroad - and who is to define "terrorist" in this context, other than our old friends the Security Services and Special Branch?
I know it's the end of August, that many MPs are still on holiday and that newspapers are full of tomorrow's anniversary of the death of the Princess of Wales. But I'm astonished by the muted response to Mr Blair's announcement of such undemocratic and ineffectual measures - ineffectual because they do not address the causes of terrorism, only its results. They are also likely to convert moderates, Irish Republicans and Islamists alike, into vengeful extremists. Mr Blair appeared close to tears when he visited Omagh on Tuesday. You do not have to doubt his sincerity to suggest that he has made a serious error of judgement. But this country's record of imprisoning the wrong people is bad enough, without making it worse in the heated atmosphere that follows terrorist atrocities like Omagh.