About 40 years ago, my brothers and sisters and I used to get a lift in the back of my grandfather's Land Rover - and we used to love it, because we could tell it was a fairly lethal way to travel. It was an ancient machine, so decrepit that the ignition key had been replaced by baler twine. The headlights were smashed. One front wheel arch was missing. The bumper was stoved in from the time the handbrake had come off and it ran down a hill into the house. The roof was squashed from the time it was nuzzled by a cow - I promise this is true - over a 10ft drop, and we found it on its back with all four wheels in the air.
It belched black clouds from the red diesel it loved to guzzle, and in the hands of my grandfather I suppose there are some who would have called it a positive death trap. In his later years, he took a relaxed view of the laws on drink-driving, and on at least two occasions after coming back from the pub, at past midnight, he had to be towed from the Exe - then thankfully not in flood - after he mysteriously turned left too early and failed to find the bridge. He was fine, of course, sleeping soundly as the sweet dark waters gurgled around him.
We loved the savage romance of the vehicle, the terrifying way it would almost tilt over as we went on the side of a hill, the surge of the revs as we tried to get through a bog. If some jobsworth police officer or other emanation of the state had interrupted our fun, and told my grandfather that he was risking our lives - well, I think we would have been disgusted and appalled.
And if this bossyboots official had told us that the peril came not from the smashed-up old Land Rover, but from the aromatic and fitful combustion of Three Nuns tobacco in my grandfather's sputum-filled pipe, I think we would have been utterly amazed.
It never occurred to us that there could be some danger involved, on those fleeting occasions when the gale carried some whiff of smoke in our direction. We had never heard of passive smoking. The pipe was part of my grandfather's life and personality, and the smell of tobacco was part of the ritual of going in his machine.
So I expect that for many people of my generation, there is something bizarre and intrusive about the notion of the Government telling us that we may no longer smoke in the privacy of our own cars. I mean, if you can't smoke in your own car, in the presence of children, then why should you be allowed to smoke in the presence of children anywhere? What about the bathroom? What about the kitchen, or any other enclosed space? The logic of this proposal is surely to allow the state to invigilate our behaviour in our own private property - and some people may legitimately wonder where it will end.
All this is to say, in short, that I understand those fine libertarian objections; and I wish to remind my fellow free spirits that this column is normally the last bastion of liberty. I have campaigned against mandatory health warnings on wine bottles and mandatory ski helmets and mandatory booster seats for children under a certain height. I have spoken out against a ban on everything from fox hunting to the right of every freeborn Englishman to make a call on his mobile while cycling.
In this case, I fully acknowledge the objections of my fellow libertarians. If we ban smoking while children are in the car, we create another offence that the police will have to enforce; we create a new category of criminal; and above all we take away personal responsibility from all those who should know better.
Surely to goodness, you might say, people these days are aware of the problem of passive smoking? Surely all smokers know that they shouldn't be puffing away in a car, while the pink defenceless lungs of children are sucking in the evil vapours?
Alas, I am afraid that people either don't know, or don't care enough. I have spent too much time in the past few years talking to doctors and to public health experts to have the slightest doubt about this one. Smoking is a massive killer in this country. It is still the biggest cause of preventable death in Britain - even though obesity is now puffing to catch up. Smoking causes cancer, heart disease, stroke, emphysema, you name it. Too many young people, especially young women, are taking it up without any real understanding of the risks, and when they do understand the risks they are akratic - they just can't help themselves.
All the studies I have seen say the same: the greater the restrictions you place on smoking, the less tobacco is consumed, and the fewer deaths you have - especially from heart disease. Of course I don't want the state nosing into our homes, but there are millions of children who are being unfairly exposed to tobacco smoke in cars that do not have the great rents in the canvas and other picturesque ventilation systems of my grandfather's Land Rover. They cannot protest, and very often the smoker in the vehicle lacks the will to stub it out.
This law would give that smoker an extra legal imperative to obey their conscience and do the right thing. And no, I don't think it would involve the police in a huge new anti-car-smoking task force, diverting them from dealing with robbery. This is one of those measures like the alcohol ban on London's buses, which has helped bring down bus crime 40 per cent in the past six years: it is largely enforced by the natural social pressure of disapproval backed by law.
So I apologise to all my libertarian chums: I am afraid on this one I am firmly with the bossyboots brigade. Ban smoking with children in the car. It is a disgusting thing to do and endangers their health. The proposal before Parliament is a good one that will save lives.