Mangold looked severe: "You've left out one clause, haven't you? What does the alpha dog do when he gets in there?" Ritter looked happy: "I said: `The alpha dog lifts his leg and pees against the wall. And when we leave a site, they're going to know we were there.'"
I'm not sure that this exchange was entirely relevant to the programme's main thrust - that Western intelligence agencies used the UN as cover for their own activities in Iraq - but you could see why they didn't want to leave it out.
Mangold had three principal allegations to make regarding the activities of the United Nations Special Commission on Iraq (Unscom), the body that sends out the weapons inspectors. First, that Western intelligence agencies used Unscom's offices in Baghdad for unauthorised eavesdropping. Second, that the US and the UK used Unscom's headquarters in Bahrain as cover for their own spying operation. And third, that information gathered by Unscom was used, illegally, to pick targets for Operation Desert Fox, last year's bombing raids on Iraq. To back him up, he had witnesses, names, dates and dinky computerised diagrams of Unscom HQ.
The case seemed pretty unanswerable, despite the fervent denials of Unscom's Australian head, Richard Butler, At one point, discussing an operation in Romania to foil Iraqis out to buy components for Scud missiles, Butler admitted that he knew of such an operation but that his inspectors had nothing to do with it. Yes, Mangold said, Scott Ritter had been involved. Butler stopped dead and stared at him for a couple of seconds before asking: "Is that a fact?" Mangold gave a very slow, satisfied nod. You imagine moments like that - when you know more about an organisation than the man running it - come rarely in a journalist's life, and you savour them when you get the chance.
One point made was that it had been impossible for Unscom to avoid getting its hands dirty: with Iraq managing to hide its weapons every time the UN inspectors appeared to be getting close to them, it had been forced to ask "friendly" intelligence services to help it gather information.
The moral seemed to be, not simply that the UN had failed in Iraq, but that failure is inevitable: if people are going to play dirty, you can either play fair and lose, or play dirty and lose your authority. For 50 years, the UN has staggered on as the last remnant of a belief that the world can be run along legal, peaceable lines. The Unscom affair looks like a nail in the coffin. In that sense, this may have been the most important documentary broadcast this year