Listening in to UN conversations would have been not only wrong - but also fruitless

I would be surprised if we did intercept the calls of Kofi Annan. I never met anyone less likely to engage in subterfuge

The only surprising feature of the decision of the Attorney General to pull the plug on the prosecution of Katharine Gun is that it took him so long. Forget all the lawyerly talk yesterday about evidential rules. The reality is that the prosecution team came to realise that if they didn't abandon the case first, any jury was likely to throw it out.

And they would have been right to do so. There was some huffing and puffing yesterday in Parliament about the Official Secrets Act now being in tatters and national security left without protection. Nonsense. There has been no recent case in which the state has been unable to secure a conviction against an employee who has sold genuine secrets to a foreign power or, more commonly these days, to a newspaper proprietor. However, juries have shown a healthy independence of mind in refusing to let the state invoke the Official Secrets Act to suppress political embarrassment rather than protect national security.

At the Prime Minister's press conference yesterday there was talk of lives put at risk, and no doubt some of the more excitable media will faithfully recycle that line today. But by no stretch of the most fevered imagination could Katharine Gun be accused of putting lives at risk. The document she smuggled out of GCHQ was not about the dangerous work in the field of a British agent spying against an enemy of our country. It was an e-mail from the Washington National Security Agency asking for help in a "surge" operation to eavesdrop on our fellow members of the Security Council. She certainly made life more awkward for London (and Washington) by putting this cynical request in the public arena, but she did not make anyone's life more risky. The worst practical consequence may have been a few extra frissons on the UN reception circuit.

It would have been more difficult to convince a jury that she had jeopardised British national security, given the reason for the request from Washington. The extra interception was to "give US policymakers an edge in obtaining results favourable to US goals." It may have been thought by some members of the jury that Katharine Gun had protected British interests by exposing such a brutally frank statement of US dominance of our objectives in Iraq.

Given that national security was not put at risk, the decision to prosecute Katharine Gun at all looks curious. The official grounds given yesterday for dropping the case look even more curious. Parliament was told that the case was abandoned because the prosecuting counsel could not reveal in court the evidence that would rebut the public interest defence claimed by the lawyers for Katharine Gun. Yet it had been known for months that her lawyers would maintain that, as a war in Iraq would be illegal, her attempt to prevent it could not be illegal. In effect, the state conceded yesterday that it did not have enough confidence in the legality of its invasion of Iraq to let a jury return a verdict on it.

One consequence of the trial being abandoned is that the rest of us do not know, and are unlikely to find out, what was the answer to the e-mail from Washington. Did GCHQ obligingly tilt its satellite dishes to focus on intercepting both the office and domestic phones, as requested, of other Security Council members? Or did someone at the top pause first to read the UN Charter, which the National Security Agency appears to have overlooked, and noted that it rendered the communications of UN delegations inviolable to interception?

If we did agree to play a part in the "surge" operation, it does not appear to have had any practical effect on the votes in the Security Council. Listening in to their phone calls may have given us a fuller picture of why the majority of the Security Council believed we were wrong in our policy on Iraq, but it does not appear to have produced enough of an "edge" in our diplomatic negotiations to change their minds.

This does not surprise me. Every Foreign Secretary becomes familiar with the exaggerated importance that is attached to intelligence because it is secret, regardless of whether it is actually of any practical value. Moreover, the capacity of the machine to produce intelligence now approaches infinity as the volume of electronic communications has exploded and the technical means of intercepting them has expanded in parallel.

During the Napoleonic Wars, interception consisted of a kettle permanently on the hob in the Royal Mail in order to steam open diplomatic correspondence. Today GCHQ fills a giant doughnut building outside Cheltenham from where it casts a giant electronic net into space to capture satellite signals. The need for a signed warrant from the relevant cabinet minister remains the only valuable bottleneck on capacity and I am encouraged to see from the annual reports of the Commissioner on the Interception of Communications that some requests for warrants are still blocked.

I would be surprised if it were true that in the run-up to the war on Iraq we intercepted the calls of Kofi Annan. I never met anyone in the diplomatic community less likely to engage in subterfuge than Kofi. If I, while Foreign Secretary, wanted to know his honest views, he would courteously and patiently explain them to me if I rang up and asked. It is my impression that in the period of intensive diplomacy which ended with the withdrawal of the UN weapons inspectors, the problem was not in establishing what was the advice of Kofi Annan, but in getting London or Washington to listen to it.

The truth is covert intelligence is of most value in gaining insights into the world of people who operate covertly and secretively. The most obvious such network today is that of the international terrorists with a global agenda. Tragically, President Bush could not have proved more wrong in his promise that the conquest of Iraq would provide a victory in the war against terrorism. On this point, our own intelligence agencies were only too right to warn in their assessment on the eve of invasion that it would stimulate terrorism.

Tony Blair was correct at his press conference yesterday to highlight the central role that the intelligence agencies now play in foiling the modern terrorist. By definition, the operations such terrorists mount on their target countries are controlled from abroad and their point of maximum vulnerability is their international communications.

GCHQ grew out of the operation in the Second World War to crack the Enigma code. Today, it can be a major part of our protection against the terrorist threat to our security. As such, it will be of much more value to the British public, and for that matter the American public, than being diverted into snooping on other members of the Security Council who posed no threat to us but who proved wiser than either the US or UK governments over Iraq.