Dr Julian Lewis: Recently, a senior figure in the anti-terrorist world addressed a conference on security issues, and pointed out that the United Kingdom and other target countries face a terrorist threat that aims to cause destruction, not in single streets, as the IRA did, but in entire neighbourhoods and, if possible, entire cities. He predicted that the threat would persist for the next 10, 15 or even 20 years, but on a note of grim optimism he predicted that life would go on and a new sort of normality would be established after hard, remorseless effort by society as a whole and anti-terrorist services in particular.

I am sure that his prediction is right, and history bears it out. In the period between the First and Second World Wars, it was widely believed that society could not stand up to the pressure of aerial bombardment. In fact, society stood up to it throughout the Blitz in the United Kingdom and, more surprisingly, throughout the much heavier attacks in the latter days of the Third Reich, when German cities were utterly devastated.

There is a tendency, because we live in peaceful times, to underestimate what society can cope with in war. No free society can have absolute security against a small group of determined saboteurs – that was one of the Home Secretary's messages in his thoughtful opening remarks. To those remarks one could add that no repressive society or dictatorship could have absolute security against such a threat, either. Again, one casts one's mind back to the occupied countries of Europe and to the French Resistance in particular who, despite enormous totalitarian forces of repression ranged against them, were still able to mount effective sabotage – or terrorist attacks, as the German occupiers would have called them.

What one can do is try to focus on the known possessors of weapons systems which, if they got into the hands of would-be saboteurs or terrorists, would enable them to wage the sort of campaign that that senior anti-terrorist figure was predicting they would try to wage, to devastate whole neighbourhoods or even whole cities.

In that connection, the most interesting paragraph of the Report [of the Intelligence & Security Committee, 2003-04] for me was paragraph 91 in the section dealing with Libya. It states:

“The detailed intelligence on Libya ... collected by the UK and the USA from all sources over a significant period of time, enabled the UK and USA to demonstrate to the Libyan authorities that they knew about their WMD programmes."

It then adds the curious comment:

"Consequently, when the inspectors went to Libya, the Libyan authorities, while they tried, were not able to hide their programmes and full disclosure was eventually achieved. This was a major intelligence success."

Yes, it certainly was, but that was the first indication that I had had that there had been an attempt by the Libyan authorities to go on with a policy of concealment, even after they had come forward and said, "We want to get rid of our weapons of mass destruction. Come in and help us do it." I should be very interested to know more of the story behind that interesting comment, and I congratulate the Committee on having teased out that titbit of information.

It must be said that the terrorist movements with which we are concerned are extremely patient. I think I am right in saying that there was a period of about eight years between the two attacks on the World Trade Center, the second ultimately being the successful one. It is all too easy for us to go into one of those periods between attacks and begin to become a bit complacent. Indeed, that senior anti-terrorist figure said that his principal concerns were complacency in society, which he described as a very great problem, and the importance of creating greater public understanding of the wide range of dangers and the long-term nature of the overall threat.

What the Libyan business illustrated in the wider context is that something sinister was going on under the surface. A report on BBC News Online on 23 May retails how North Korea had been involved in sending uranium to Libya. It states that the International Atomic Energy Agency

"had found evidence that Pyongyang provided Libya with nearly two tons of uranium in early 2001."

A spokesman for the IAEA, Mark Gwozdecky, told BBC News Online that the investigation

“‘spans three continents and involves entities or individuals in at least eight countries’.”

That was all linked to the plot by A.Q. Khan, the father of the Pakistani bomb, to sell nuclear secrets to Libya, Iran and North Korea.

Another report on the BBC on 28 May is headed "UN continues Libya nuclear probe" and states that the IAEA has said that

"questions remain about Libya's nuclear weapons programme, despite the promise last December to scrap it."

A report from Associated Press back in February commented on a firm in a place called Shah Alam in Malaysia. The firm, ironically enough, is called SCOPE – nothing to do with the new system that was described earlier in the debate for intelligence collation in this country. It is a precision engineering firm that was part of the network and was involved in machining the parts of the centrifuges that the rogue regimes, in particular Libya, planned to use to construct their bombs. Worryingly, at the end of the report the company's spokesman said that if it received an order similar to the Libya shipment, it would have no reason to turn it down. The spokesman commented:

"Milling and cutting is the same today as it was before".

It is not good enough for the Government, or even for the Committee, periodically to state that successes have been achieved, that terrorists have been disrupted and that we have been saved by the good efforts of the Security and Intelligence Services. Something more than that is required. If we are to obtain the greater public awareness, concern and realisation of the long-term threat, which senior counter-terrorist figures feel to be necessary, we must have authoritative accounts of what has been going on as soon as the information can be revealed. We should not have to depend upon putting together a jigsaw from individual, isolated press reports, such as I have been quoting. We should have a system whereby the Government publish from time to time, perhaps in the form of an annual report, an account of what can be revealed about those operations which have been frustrated or exposed.

In the brief period remaining, I want to address some of the remarks about Iraq. When I congratulated my hon. Friend the Member for Chichester (Andrew Tyrie) on his thoughtful speech, he said, "I am sure that you do not agree with half of it." I replied, "You are right, but there is one thing that I do agree with in particular, and it is the most important thing – the British people must always be told the truth." If a democratic Government do not tell the British people the truth, even in a good cause or because they think that they have a good reason not to do so, they will destroy the trust on which their support depends.

I have said this before and I will say it again: I wish that the Government had not fought shy of telling the British people the real reason why war against Saddam was essential. It was not because Saddam was about to attack anybody; it was not because he had attacked anybody; and it was not even because of his humanitarian record of atrocities. Those are the traditional justifications under international law, as it currently stands, for intervention.

War against Saddam was essential because the events of 9/11 showed that the world now contains groups that would unhesitatingly use WMDs, if they could get them, and thus cannot be deterred. This has lowered the threshold for intervention against rogue regimes that have a track record of trying to obtain WMDs. That probably does not conform with international law, as it was explained to the Government at the time that they took the decision, and they therefore felt that they had to massage the facts.

International law is not static; it evolves, and Governments must help it to evolve. It would have been better if our Government had helped international law to evolve by saying clearly to the British people that we did not know what Saddam did or did not have, but after 9/11 we could no longer take the chance.