What to make of it? A government that has seen fit to pronounce recently on issues from World Health Organisation child-growth standards to the Grade I listing of Crystal Palace dinosaurs, from a “Jobs boost for Fife” to a national Playday, remains firmly silent on the climate change protest at Heathrow. All Gordon Brown’s spokesman has been prepared to say is that the protesters were “a matter for the authorities and those who ran Heathrow with regards to disruptions. People did have the right to protest, but the Government felt that any action that disrupted the operation of Heathrow would be unacceptable.”

It’s a tricky one for the Government, this. Because if you cared about climate change, you would have to wish the protesters well. But then if you did that, you might upset the business lobbies demanding bigger, better, more Heathrow. You might suggest that you cared about something greater than “productivity”.

So you sit on the fence and focus instead on imaginary fears, hyped up by BAA, the airport operator, that protesters intend to storm runways and disrupt hard-earned holidays for “ordinary families”. The police help, by treating people armed with tents, guitars and toilet rolls as if they are terrorists, abusing anti-terror legislation to subject them to intensive searches. And the media weigh in too, of course, running pictures of the most dreadlocked, dirty and bedraggled camper they can find, preferably with scruffy children attached.

Even then, however, the media are challenged to find the stereotypical campaigner they crave. This one turns out to be a professional, that one works nine-to-five and has taken a week’s holiday to be there, that couple own a nice home down the road. They all seem to be the children of teachers and army officers. Thank goodness for the long haired – sorry, “wild-haired” (Daily Mail) – fiftysomething who once superglued herself to the headquarters of lastminute.com.

Even the environmentalist vegan family, who have brought their four children aged 2 to 9 to the camp, have proved a challenge. Why? First, because they are marrried, ergo responsible. Secondly, because she is a “full-time mother”, as the Mail put it, which in right-wing newspaper terms represents the world as it ideally should be.

Irresponsible, smelly hippies, or ideal family? Eco-terrorists or suburban middle-class voters? Dangerous idealists, or kids of the kind of people who brought Labour to office? You can see why politicians have sat themselves firmly on Heathrow’s perimeter fence: these protesters are not so easy to pigeonhole.

Until, that is, there is violence. As soon as the Heathrow demonstration turns aggressive or seriously disruptive to ordinary travellers, the politicians will be able to climb down off their fences: condemn the violent element, ignore the main argument. It is one of the many reasons to hope that the protest remains peaceful.

For what’s the argument about? It’s about a third runway, a rise in flights from 473,000 to 710,000 a year, it’s about the 31 million tonnes of carbon dioxide that Heathrow flights already pump into the atmosphere each year. I don’t know anybody who thinks that that’s a good idea. I don’t know anybody who doesn’t view Heathrow already as a stinking heap blowing a polluted hole in part of the South East. Who would go anywhere near it if they didn’t have to? Pretty much anyone without shares in BAA would not wish another runway on that particular part of England (if, indeed, upon any of it).

And hasn’t the political consensus, we are told, already moved the protesters’ way? Haven’t even the US Republicans agreed that we cannot go on flying and driving and belching out carbon emissions the way we have done? So why not wish the protesters well? What is there seriously to argue about? Where is that nice Dave Cameron, where green Miliband, where eco-Brown, today?

Or were they never really quite so green? When he was Environment Secretary, David Miliband proposed a bold system of personal carbon allowances. Each person or household would be given an annual quota, to use or to trade. Wealthy people who wanted to fly frequently could buy some of the quotas off poorer families. Government has gone quiet on that one.

I would take the idea even farther; couldn’t we stack up allowances from year to year, then use them for one big family holiday, or even “save” them to leave as inheritance for the next generation? Being an ordinarily selfish middle-class mother I can think of few things outside the immediate cost that would actually stop me taking the next long-haul flight; but being told that my decision to explore the world today will directly prevent my daughter doing so tomorrow, would swing it. To be told that I had to save up a carbon allowance for her future use would keep the car at home a little more often.

Your holiday this winter or your daughter’s gap-year trip in a decade’s time – a direct, personal bribe with our children’s future freedom. Our generation has had it so easy in terms of exploration and travel. It is time that a politician had the guts to confront us with the real cost of that.

The trouble is that the protesters don’t vote. The climate-camp literature claims that voting just perpetuates a fundamentally corrupted political system. And thus what ought to be the protesters’ greatest weapon – the power of the ballot box, flawed as it is – is lost, and all that is left is the anticapitalist dream of overthrowing the entire political system. Which is why the politicians can sit this one out perfectly comfortably on their fence.

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