ON Monday we had a “free vote” (at least Conservatives and Liberal Democrats did).

Of course, all votes are free votes, in the sense that nobody can force a member of parliament to vote for, or against something and every MP exercises his or her own judgement and conscience.

The only difference is that it was not a whipped vote: the Government whips did not take up their places in the doorways of the appropriate division lobby to indicate in which way they were encouraging their colleagues to vote.

Equally, ministers could vote entirely as they pleased without fear of having to resign if their vote breached government policy and the principle of collective responsibility.

Similarly, ambitious back bench MPs could vote as they pleased without risking their chance of promotion by being thought “unreliable”.

So, if all votes are really free votes, why have whips in any event? I think the answer boils down to two essential reasons: first, in order to ginger them up and get MPs there to vote at all, whichever way they end up voting.

There are any numbers of other demands on MPs’ time both at Westminster and in the constituencies. So, every week the whips send out a timetable indicating when votes are likely and reminding MPs that they need to be there unless they have sought and been granted leave of absence.

If we didn’t do that, and add daily reminders by email too, MPs would get caught up in important meetings and fewer would end up voting.

Equally, if we didn’t take our MPs to task when they miss a vote, it could soon become a habit.

Also, many votes are on highly technical and detailed amendments to legislation.

In their busy schedules, and with so many demands on their time, many MPs may not have been following a particular debate, and will quite naturally look for guidance from their party.

The free vote this week was on a Lords amendment to the Children and Families Bill which returned to the Commons for approval or rejection.

The amendment sought to ban smoking in motor vehicles in which children are present. So, why was it a free vote?

The straightforward answer is that it defies the two reasons above that I have set out to explain the need for whips.

Firstly, it is the sort of thing about which people feel strongly one way or the other, and so they will make the effort to be there unprompted.

Secondly, it is one of those things about which even people who share the same political ideology and outlook disagree profoundly.

Some hate the idea of the “nanny state” interfering with your actions in your own private space. I have strong sympathy with this view.

The key difference, however, is the presence of children and my own childhood memories of the unpleasantness of sitting in the back of a car while an adult was smoking in the front. So I voted to ban it.

I wouldn’t go so far as to ban it in the home, however. Why the difference?

It comes down to enforcement: a policeman can see very well that you are smoking in a car with children present without intruding on your privacy.

But to enforce such a law in the home would require a level of intrusion that I do not think we could tolerate in a free society. To have tried to whip such a vote would have been like trying to herd cats, but then quite a few votes have been equally difficult to whip recently.