And nobody mentioned the green issue. Now isn't that strange? Ken Livingstone, the London Mayor, who is resolutely committed to his blueprint for a sustainable city with zero-carbon emissions on new developments and £25 taxes on fuel-inefficient cars, turns out to have five children by three different partners, and not a peep from Left or Right about overpopulation. Funny that.

A guy buys the wrong sort of vehicle, runs it for a few hours each week, most of the time it sits in his garage doing nothing, using nothing, consuming absolutely nothing, and he's a monster. Ken introduces five people into the world, people being the single biggest factor in the consumption of resources, people that need water, energy, food and shelter, that overcrowd the cities and invade the countryside, that cause CO2 emissions and generally stuff the place up and will continue doing so for roughly the next 75 years, and not a murmur.

“I don't talk about my private life,” said Livingstone, when the news came out. “It is not a relevant factor.” Except he has no private life. None of us does. The environmental lobby has seen to that. Everything we do now is political, every action matters. What car you drive, the type of house in which you live, the clothes you wear, the coffee you drink, the journey those potatoes you are buying took to market, whether you flush the toilet after having a pee, everything is now up for judgment by a finger-pointing, finger-wagging community of ethical experts that include the London mayor (who in June 2005 advocated letting yellow water stand until something more solid came along). So Ken wants a say in your toilet etiquette, but knocks five kids out in three relationships over little more than a decade and a half and tells the world to mind its business.

It must be said that Ken does like to make full use of his privacy. On February 8, 2005, when he had his little tear-up with the reporter from the Evening Standard, Ken claimed that because he was leaving a function and wearing an overcoat, he was no longer on duty as mayor and this, too, was a private affair. That the jolly-up in question was financed by £4,000 of mayoral fund cash, with invitations issued on Greater London Authority headed paper, suggested his defence could have been pulled apart by a first-year law student with his dander up; but most folk seemed to buy it, just as few have played join-the-dots with Ken's green commitments, the issue of overpopulation and the resultant responsibility of men not to be on nodding acquaintance with everyone from the midwife to the cleaner at the local maternity ward.

Nobody knows if Ken's children were planned, but as two were born weeks apart, there may have been some element of surprise. Either that or he really likes kids and so do many of the women he meets, which is handy. What cannot be explained is how Ken thinks his life and its toll on the environment is private, but the life and toll of a guy in an SUV is not.

Left and Right are largely silent on overpopulation because it impinges on powder-keg issues such as freedom of choice, state interference, sexual politics, the little ones (aren't they precious), abortion, immigration (because 70 per cent of projected UK population growth is predicted to be imported) and many other subjects to be avoided at parties, much like cheap port. We think overpopulation is something that is happening in the developing world, yet it is a far greater problem in the West. In 2003 28 barrels of oil were consumed per 1,000 people in the UK, and 68 barrels per 1,000 in the US. The same number of people in India consumed two barrels, putting into perspective the scaremonger stories about the perils of industrialisation in Asia. Even if Indian oil consumption has quadrupled, it will still be nowhere near what a family with five kids will get through over here.

The UK population stands at 61 million, which the Office for National Statistics predicts will rise to 70 million by 2028, 77 million by 2051 and 85 million by 2081, by which time 15 million more homes will be required. And last week, Brian Paddick, the Liberal Democrat candidate for mayor, said he dreamt of a day when using a private car would be considered antisocial, yet made no mention of whether having five children might be, too.

I'm not anti-kids. I've got three boys, including twins. If you have a big family, for which you take financial responsibility, then good for you. But I am uncomfortable with being judged on every trip to the shops, the toilet or the wardrobe by folk whose commitment to green issues often stops at the place it starts to affect them. I reread Thom Yorke of Radiohead bemoaning the carbon footprint of rock tours in The Guardian 18 months ago; then I clicked on Radiohead's current tour schedule. West Palm Beach, Tampa, Atlanta, Charlotte, Bristow, St Louis, Houston, Dallas, Dublin, Paris, Barcelona, Nîmes, Milan, Neuhausen ob Eck, Scheessel, London, Glasgow, Manchester, Amsterdam, Roskilde, Werchter, Arras, Berlin, Chicago, Indianapolis, Cleveland, Montreal, New Jersey, Toronto, Vancouver, Auburn, San Francisco, Los Angeles, Chula Vista, Santa Barbara and Tokyo. Get about a bit, don't they?

The tour that promoted the Hail to the Thief album was conservatively estimated at being responsible for 7,581 tons of CO2 emissions, the negative equivalent of 50,000 trees lasting 100 years each. After this the band pledged to do all it could to be as carbon neutral as possible. But I understand. Radiohead are musicians, they want to play music; and the guy eschewing the train for his car might have his reasons, too, and could probably do without a lecture. That is my point. We trade vices. Heather Mills, a vegetarian, recently turned meat production into a green issue, but no doubt regards transatlantic commuting to appear in celebrity ballroom dancing shows as pretty damn essential.

We run a family saloon on diesel and recycle all we can but, when work demands, I still jump on a plane, as do Thom and Heather and Ken. Sorry. I'd like to be pious but in the end, we barter our weaknesses and preferences and it all depends where you, personally, draw the line. For some it is 4x4; for others five by three.

Martin Samuel is the British Press Awards Sports Journalist of the Year

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