Tony Abbott's decision to wait until the Parliament had shut down at the end of last year before making it clear that he would block a conscience vote on any gay marriage bill could cost him in the long run.

It can be a mistake to decide how to vote on something you haven't even seen. Alexander Downer made this mistake as Liberal leader when he took the shadow cabinet to that famous hotbed of Liberalism otherwise known as Burnie in Tasmania. In their collective wisdom, they decided the party should vote against whatever bill then attorney-general Michael Lavarch produced to override Tasmania's anti-gay laws.

As a shadow minister at the time, I was given the task of talking and talking and talking until finally we could allow the bill through ''on the voices''. That is, everyone could say what they like on the record but when the vote came we Liberals had to remain silent and not call a division. It is a humiliating position for a great party.

But there is another problem. One of the things that really aggravates members of Parliament is when a leader announces, through the media, a decision that has been made after Parliament has risen. As there is no party-room meeting over the break, the leader's announcement and policy position gets all the airplay and permeates the public mind. MPs who disagree with the decision rightly see the timing as a tactic to weaken them.

If members disagree, what do they do? There is no party meeting at which they can vent their anger. No chance for them to collectively express their view to the leader. In these circumstances the leader and shadow cabinet are seen as strong-arming the party room.

MPs are deliberately put in the uncomfortable position of not being able to hear the collective party-room view. Some may ring around to their mates, but they know it will make little difference. If they voice their concern to the media, through which they learnt of this decision, they would be branded as disloyal trouble-stirrers. So they just have to internalise their frustration at feeling tricked or taken for granted.

The fact that there may be a vote on gay marriage in the Parliament this year is no surprise. Ever since the issue was set down for discussion at Labor's national conference in December, a parliamentary vote has been on the cards.

Many Liberal MPs would, quite properly, have assumed there would be a conscience vote. The Liberal Party prides itself on the right of members to follow their conscience. It is a cherished Liberal principle. Liberals have always been more likely to have a conscience vote than the strong-arm, collectivist Labor Party.

Indeed, there has never been a substantive policy issue (as opposed to a procedural one) where Labor has had a conscience vote and the Liberals have not. There have been quite a few where the Liberals have had a free vote and Labor has not.

So, this is Abbott's potential problem. Everyone knew there would be a vote at some point, and he waited until the troops were dispersed to announce that he did not want a conscience vote. It looks, smells and walks like a leader deliberately shutting the party room out of a decision. MPs will not warm to it.

But that is not his only problem. He told Australians his team went to the last election with a policy opposing gay marriage. That is true. But in fact he exercised a leader's prerogative and decided with the shadow minister that the Liberals would stick with an anti-gay-marriage policy and therefore not allow a conscience vote if the issue arose. It was not a policy that went through a party process.

There are, of course, many times when policy has to be decided without party-room discussion. But for Abbott, deciding this policy as leader was unfortunate. His conduct as health minister led many women to worry that, given the chance, he would use whatever power and influence he could to implement his more conservative views.

He has told Australians that if elected he would not let his personal views dictate policy; nor would he take instructions from Rome. He said these things because he is conscious of the apprehension among women and liberals that he would take Australia to a more conservative position than we now have on issues such as abortion and gay rights. So, the last thing he needs is to act in any way that causes women and liberals to doubt his word. Announcing that he did not want a conscience vote when his party members had dispersed is difficult to explain away. It looks deliberate. Even tricky.

While things are going well for Abbott and the Coalition - as they certainly are at the moment - it perhaps is not important. But politics is nothing if not unpredictable.

Yes, Abbott is working hard and doing well. Yes, Julia Gillard's unpopularity is giving an extra boost to Coalition.

But we are still potentially nearly two years from an election. What if Labor returns to Kevin Rudd as leader and public opinion washes back to a leader who Australians think was badly treated by his party?

On gay marriage, Abbott has a chance to redeem the situation. He should say he will look at the issue if and when it comes to Parliament. And he should give the party room the conscience vote that should never have been given away.

Abbotts Stance On Gay Marriage Looks Like Strongarm Tactics