She is not always reliable - indeed, sometimes infuriatingly unhelpful - but on balance I adore Iris. "She" is the acronym of the Iris Recognition Immigration System, the fast-track for passengers arriving in Britain. Thanks to Iris, you can (usually) bypass passport queues and leap the UK immigration hurdle in the blink of an eye. The really startling thing is, though, how few business travellers seem to know about her.

First, allow me to explain what Iris is not. The system is entirely independent of "smart" passports. All new UK passports contain a chip with biometric data, but at present the only information it bears is a digital scan of your photograph.

Other biometrics, from the geometry of your hand to your fingerprints, are in various stages of analysis. But for businesspeople hoping to accellerate their progress around the world in the first decade of the 21st century, the one that counts is your iris. The unique pattern between the pupils and the whites of your eyes can be captured and crunched, numerically speaking, by laser readers. This information is stored on a database of registered travellers. So when you show up and open your eyes for the scanners, the authorities know who you are, and that you are a trustworthy type.

The pioneers in Europe were the Dutch, who established the Privium system early in the century. Business travellers queued up to register, in order to avoid queuing up for immigration at Schiphol airport in Amsterdam. Indeed, travelling executives were even prepared to fund the exercise, paying €99 (£70) for the privilege of a year's membership; money well spent for passengers who passed through Schiphol every week, working out at less than two euros a trip to circumvent the endless queues of stag and hen parties heading to Amsterdam for the weekend.

Britain's version has proved more complicated to introduce, not least because we have numerous big international airports rather than just one as in Holland. But now she is here, Iris is especially appealing - because she is free.

Iris was established primarily for frequent business travellers from outside the European Union, providing a bypass for the lengthy lines for non-EU citizens. But there is nothing - except apathy - to stop British travellers enlisting, too.

All you need to do is arrive at your key UK departure airport a little earlier than usual next time. Heathrow, Gatwick, Stansted and Manchester all have Iris registration points signposted after the security check. If the office is open - and from my experience that may not be the case even during official business hours - you have your passport checked, a few cursory questions asked and your irises scanned. Once signed up, you can irritate your fellow flyers (especially if you are travelling with colleagues) by heading for the glass cube to one side of the Immigration hall. Wave your hand on the green arrow and the doors should glide open. Look into one of the scanners angled up towards your eyeline, and - after a bit of messing about to get in the right position - the exit doors should open.

It looks like a "win-win" arrangement: good for you, because it helps you dodge interminable queues; good for officials, because it saves them wasting time on the majority of travellers who are believed to pose no threat, and concentrate on those they are not so sure about. Not everyone is comfortable with what amounts to a two-tier system: some say it unfairly disadvantages infrequent travellers, and may make them susceptible to undue scrutiny.

Those have tried it will conveniently put such concerns to one side, so enamoured are they with the special touch of Iris. Henceforth UK Immigration will be a breeze, except when you enter via one of the airports where Iris has yet to appear - or encounter one of the slightly too frequent failures of a system that may be too fickle for some. But, hey, to err is only human.

For more information on the Iris system see