Every once in the while we think we are glimpsing the outline of one of those ‘great debates’ on a major issue of our time which politicians, officials and voters routinely call for… Europe, educational values, the environment, inter-generational transfers of wealth. Then the clouds roll in and the topic disappears from view again.

I thought I caught one such glimpse the other evening when the TV monitors at the Commons showed Ruth Kelly and her shadow transport stalkers, Theresa Villiers for the Conservatives and that tenacious Lib Dem, Norman Baker, discussing what was billed on-screen as ‘Heathrow’.

“That’s a pretty quick response to the shambles at Terminal 5,” I told myself, eager to be impressed by new parliamentary procedures like topical questions. But no, the Lib Dem-inspired debate was not that nimble on its feet. MPs, mostly London ones, plus a few long-haul Scots, were discussing a more established topic: the third runway which ministers are edging towards sanctioning at Europe’s biggest, bulging airport.

Let me declare an interest here. From where I live in West London I can see the planes descending into Heathrow, but usually have to strain to hear them. If the third runway is eventually built it will change my life, provided Britain’s speeded-up planning process is fast enough (they built Beijing’s vast new airport in the time T5 took to plan) for me to have survived the experience.

With luck I’ll be quite deaf by then. But, until recently, I accepted the economic case for expansion with no enthusiasm but with resignation, despite the bad faith which has long accompanied Whitehall’s prevarications about Heathrow. Remember that 480,000-flight-a-year cap which then-transport secretary, Stephen Byers, announced when T5 got the all-clear in 2001. Just two years later the white paper signalled the first wriggle.

But that’s what great debates are about, surely? The facts change, so we change our minds – sometimes. What’s changed since 2001 is a lot, and the facts pull most of us in both directions. Public demand for low-cost, long-haul flights has grown near-exponentially. Heathrow’s rivals – notably Charles de Gaulle and Schipol – have seen its darkening reputation as an opportunity.

“Where will London’s next runway be?” I then recall asking to prominent aviation figures at a party. ‘’Stansted, they’re all Tory seats,’’ said one cynic. “Schipol,’’ said the other with even crisper brutality. Well, Stansted’s new 3,000m runway was still on course for 2013-ish the last time I looked. But demand for flights grows voraciously and both Whitehall and the business world agree there is no alternative to Heathrow expansion.

And yet the case made in the Commons by London MPs of all parties to question that assumption was impressive on both economic and environmental grounds. The terrier-like Ms Villiers and dogged Norman Baker attacked each other’s position – the Tories are badly split on the issue. Both argued forcefully that ministers are yet to provide convincing answers on key questions. What sort of questions? Nowadays they include more than the ever-expanding noise footprint if 480,000 flights are to become 720,000. What about CO2? What about better management of air traffic control to prevent all that time-and-fuel-wasting stacking? What about better use of high-speed trains?

All good questions, worthy of that familiar phrase, ‘integrated transport strategy’. In fairness to John Prescott, the fact that the new St Pancras International station opened on time and in good order – as BA’s chief executive, Willie Walsh, probably noticed with a grimace – is due in no small measure to the Prescott rescue package for the high-speed link.

But we still never feel there is a convincing big-picture strategy out there, more a series of little pictures that can easily be shaken off their picture hook by a sharp bang on the wall. Someone pointed out that Heathrow is the world’s only major airport on an east-west axis over a major city, that it’s simply in the wrong place and ought to be out over the sea somewhere in the Thames estuary or a land-based compromise at Cliffe in Kent. Expect Kent MPs to oppose that one. They already do, though Thames Gateway strategists do not.

Oh dear. When St Pancras opened, I told a chum: “We seem to be doing big public sector projects properly at last – as the French have done for ages.” As the hapless Willie Walsh can confirm, I spoke too soon. Not only a disaster at T5, but a badly-handled disaster. Think Metronet again. Must do better.

Michael White is an assistant editor (politics) of the Guardian