I won’t be voting to raise the age at which it is lawful to purchase tobacco.

I don’t subscribe to the view that it is proper for the state to direct us to do things that are good for us, or to abstain from things that are bad for us. Providing warnings or encouragement is one thing, but giving us orders is quite another.

A number of journalists have demanded to know how I can continue to support the Prime Minister as leader of my party when such a profound philosophical difference has emerged between us.

Well, first, the PM made it clear that any vote on this question would not be whipped, so the pressure is off; it is purely a matter of conscience.

Second, democracy is messy: There will always be substantial disagreements on matters of principle within our political parties, and more so in the UK.

Our voting system ensures that, to have any chance of success, a party must have a broad base of support.

Proportional voting systems on the continent however, enable their parties to maintain much narrower ideological purity and still secure representation.

The consequence is that multiple parties have to forge a coalition after an election and negotiate a programme for government that was never put to the voters.

The virtue of the UK system is that we make our coalitions before any election, in that each political party is itself a coalition which puts its manifesto to the judgement of the voters.

Inevitably, our ‘broad church’ polity means that, though united on most issues, our political parties will have significant disagreement on others.

So, back to tobacco.

I don’t doubt that had we known the dangers of tobacco when Sir Walter Raleigh first introduced it to England in 1582 it might well have been banned, but it’s too late now.

The experience in USA of the Prohibition era from 1920 to 1933, where attempting to ban a widely consumed product, in that case alcohol, gave rise to a crime wave, violent gangsterism and widespread flouting of the law, is a warning of how this might play out.

It is one thing to demand that youngsters prove their age, but as the age threshold rises year by year, are we really going to ask the retailer to distinguish between one old man who is entitled to purchase a packet of cigarettes, and another old man, albeit one year younger, who isn’t?

Are we really going to make sure that someone, now aged fourteen, is prohibited throughout his life from enjoying the luxury of a cigar on New Year’s Eve?

Is this really the business of government? Aside from rescuing us from ourselves, the principal argument for prohibition is the scale of cost that falls upon the NHS through treatments for smoking-related disease.

I accept that there is a logic to this. We have developed a system of socialised medicine where we share the cost of any individual ill-health among all tax-payers.

It follows that anyone who recklessly endangers their health is a burden upon all the rest of us. Does it follow therefore, that we have the right to prevent them?

It may be logical, but it is the thin end of a very thick wedge.

Its logic would soon extend to an absolute ban on smoking, and, so proceeding, to alcohol, and to any number of other products that food fascists have on their agendas.