Dad's Army scenes at the United Nations as Captain Mainwearing tries to contact Godfrey

It is bad form to laugh at a funeral, but sometimes the tension is too much for the mourners and smothered chuckling breaks out at the most inappropriate of moments.

So it was in the public gallery of the United Nations Security Council yesterday. Just once or twice, gravity and foreboding gave way to amusement. "Hello! "Hello!" "Hello!" "Go ahead". So begun a radio conversation between two Iraqi army officers intercepted by foreign intelligence agencies and played yesterday by the US Secretary of State, Colin Powell, to the 15-member Council.

The two Iraqis seemed to be having trouble communicating. This short excerpt and another of the same ilk broadcast through the somber chamber perhaps made for the most compelling minutes in the 90 minute-long seminar given by Mr Powell yesterday. More than anything else he had to give us, in fact, these tapes seemed to offer us the most reason to conclude that Iraq is in blatant violation of international disarmament obligations. The translations of the Arab conversation between the officers were projected onto two giant screens at the back of the chamber. Mr Powell wanted to make sure we understood exactly what was being discussed. An order is given by the senior officer to his subordinate to stop making any mention of "nerve agents" in communications between them.

The implication was clear - that the agents do exist. And yet, in my area of the press gallery, the reaction was a brief eruption of titters. The script, in English translation at least, simply had the air of a vintage episode of 'Dad's Army'. Captain Mainwaring is trying to get a vital message through to Godfrey and Godfrey, a fine but aged fellow, can't hear properly. Mr Powell, his voice occasionally cracking from the exhaustion of weeks of relentless diplomacy on bringing the world round to Washington's view on Iraqi defiance, did not hear the giggling. As he glanced occasionally from his text, however, he may have detected something else.

Certainly, most of the other nations - most of them represented by their foreign ministers rather than the usual ambassadors - were listening with great seriousness. But none of their faces betrayed shock or surprise. With all of his postulations about Iraq's evil ambitions, with all of his natty graphics and satellite images on the twin screens and with all of his revelations of secrets revealed by intelligence sources on the ground, he failed to provoke that one instant that surely he wanted the most.

What did not come was a moment when the air in the chamber was charged suddenly by a collective gasp of surprise or of shock. Tired eyes in the press gallery would occasionally track back to the man at the centre of the horseshoe where the council sits where Joschke Fischer, the German Foreign Minister, with startling red tie, was seated. It a quirk of protocol timing Germany has the presidency of the Council for this month. And Germany has made quite clear its aversion to any Anglo-American march to war. Mr Fischer, quite frankly, looked a trifle bored most of the time. He rested his head on his hands, rubbed his eyes.

Jack Straw, the Foreign Secretary, did not look bored. He nodded his head with appreciation when Mr Powell recalled the police raid on a suspected terrorist cell in London last month and the murder of a British police officer. You wondered why the seat to Mr Straw's left at the crowded table had been left empty until you saw the next delegation along was from Iraq. It was better to leave space between them. Perhaps Mr Powell foresaw difficulty in keeping the attention of his audience. His projections were impressive, each slide preceded by theme headings in bold, gold letters in CNN-style. He had his satellite photographs, but they did not make for good theatre. They were grainy and while Mr Powell explained their significance, we were not quite sure to accept his interpretation. That bunker, he said, would have been teeming with Iraqis minding weapons of mass destruction. But how does he know?

He had tried, to be fair, to lower expectations before his presentation - which President George Bush announced in his State of the Union address last week - by conceding he had no "smoking gun" to share with other nations. Yet, the risk was always there that his appearance would be deflating. The only moving image he had was of an Iraqi jet spraying vapour of a black-and-white landscape apparently in a trial of spraying chemical or biological agent. But the clip, as he admitted, was ages old.

There is theatre, however, in the flourishing of a little vial of white powder and asking us to believe that it is anthrax. Well, it did get our attention. He had better be kidding, because an involuntary loosening of his fingers and the vial would be dropped the floor. And we would all be likely to die. It was a trick aimed not just at us, but also at the millions of TV viewers across the United States who also were watching or would be seeing reports of it on the evening news. That is the clip the news editors would surely use. And no one should forget that Mr Powell was speaking to the US public as much as to us. As much as providing evidence, Mr Powell was trying to cajole the other council members.

Some may not have taken kindly to his tone of admonishment. Did he really need to use the projection screen to display, word for word, a key paragraph of the resolution passed by the Council in November last year? "This is what we agree," Mr Powell wanted to say. He was not speaking to underlings at the State Department but to fellow foreign ministers. They know full well what the resolution states. And none of us, by the way, will be able to forget Mr Powell's presentation. We, the UN correspondents, now have our personal computer disks containing all of the Secretary of State's exhibits, including the conversations and the graphics and images. "Iraq - Failing to Disarm. February 5, 2003."