The construction of the thing is impressive. There is to be a new spur off the M25 to take passengers in directly (British Airways passengers, of course, the rest of us will have to get off at the M4 exit and take our chances), and the terminal building (or buildings, rather, as it comes in two parts, with a secondary T5B a hundred yards away, connected by an underground railway) rises up out of the suburban houses. The route in on a BAA bus took us through the village of Sipson, with its charming thatched houses and charming NO THIRD RUNWAY placards.

Of course, what you expect from Heathrow these days is delays, and the trial duly delivered. Everything went swimmingly until, having passed security, it suddenly became apparent that there was nowhere to go. The signs to the gates were clear, but there was no gate number on the boarding pass, and no information screens working.

Predictably enough, the computers running the screens are running Windows. And it wasn't playing ball. So 2,000 fake passengers sat around watching the Windows XP startup screen appearing, then disappearing for 40 minutes. That gave us a chance to wander around the place, although in truth there isn't much to see. The shops weren't open, but even if they were, it's the same old names you'll see at every other BAA joint.

That sideshow finished, the flight information found its way to the screens and everyone was off again. It was only a test, admittedly, and a test designed to show up that kind of problem, so in a way it worked. But it was nice to see that even a brand new terminal isn't immune to Heathrow's delays.

EDIT: The trials are continuing for another four months so there's time to sign up if you'd like a nose around before it opens at the end of March.