In the run-up to Christmas, I lost count of the number of events I went to that were subject to the Chatham House Rule. An after-dinner speech here, a political talk there, and a luxury-brand conference in between. Often, there's little that's worth repeating anyway, and the rule is usually only invoked by the sort of second-tier politicians and finance directors who see no currency in either a) being sued for slander, or b) exposing their business practices to all and sundry (or, at least, to those of us in the badly dry-cleaned monkey suits, huddled round the cheap wine and the BSE-friendly food).

The rule was devised at Chatham House back in 1927, with the aim of providing anonymity to political speakers. The Royal Institute of International Affairs, as Chatham House is officially known, was founded in 1920 to "stimulate debate and research into political, business and security issues", and remains independent, a non-profit, non-governmental organisation whose funding comes from charitable grants, corporate donations, subscriptions and revenue from the institute's trading subsidiary.

It's still based in St James's Square, in the heart of London, in a listed building that was once home to three Prime Ministers (Pitt the Elder, Edward Stanley and William Gladstone, all of whom could have benefited from invoking the rule at one point or another). In my naivety, I'd always thought that the rule meant that nothing heard was allowed to be repeated, but after investigation, I realise that it's simply the source of the material that must remain hidden. "When a meeting, or part thereof, is held under the Chatham House Rule, participants are free to use the information received, but neither the identity nor the affiliation of the speaker(s), nor that of any other participant, may be revealed."

There will always be those who claim that the rule is only invoked when people are up to no good. The Freedom of Expression Institute in South Africa recently wrote to the University of Pretoria to complain that a forthcoming college conference on terrorism and counter-terrorism was being held behind closed doors, and that "the Chatham House Rule is not a politically neutral instrument for the facilitation of free debate". But the big problem is the fact that few people take it seriously any more.

In September 2004, the British ambassador to Rome, Sir Ivor Roberts, heaped embarrassment on Downing Street and his diplomatic superiors at a closed-door conference in Tuscany, conducted under the Chatham House Rule, when he described George W Bush, the US President, as al-Qa'ida's "best recruiting sergeant".

Some of us, though, believe that rules are rules, so every word uttered recently by Michael Portillo, John Humphrys, Trevor McDonald, Adam Crozier and Michael Howard will have to remain confidential. Until, of course, I decide otherwise.

Dylan Jones is the editor of GQ

d.jones@independent.co.uk