Sex is the greatest accelerant in political stories. Tossing bonking allegations into a story from Parliament is like throwing petrol on a fire: stand well clear because there is likely to be collateral damage.

So it is with former MP Richard Worth. Worth's political career imploded spectacularly but he wasn't the only casualty. All involved suffered. Neelam Choudary, the Labour Party activist who claimed Worth sent her allegedly saucy texts, was soon unmasked publicly and the somewhat chequered business background of Choudary and her husband was exposed.

Labour Leader Phil Goff had the whole affair explode in his face and he remains tainted by National's counter-allegations of dirty tricks by Labour.

Although now rid of the accident-prone Worth, John Key is not rid of the big searching question continually being asked by the media. What exactly did Worth do to have his Prime Minister lose confidence in him? Key will not say, despite repeated questioning . The incessant harping on this theme at times completely obscured other messages the Government was trying to push.

Just as Key's stonewalling seemed to be working and the Worth question was fading, news broke that the Korean woman at the centre of the second scandal was withdrawing her complaint against the fallen ex-MP. Now the questions will reignite. Why did Key lose confidence in Worth? Why did he have to resign? Was he the victim of a Labour smear campaign? Did the Government make Worth some kind of sacrificial lamb to get the media off its back?

The Korean woman who now, it seems, feels Worth has suffered enough by losing his career, is also beginning to feel the heat, with questions about her business affairs and an allegation she made against another businessman.

The fallout from a political sex scandal spreads wide but for Key, the worst effect will be that he again comes under pressure in the House and in press conferences to explain the reason he lost confidence in Worth. Frankly, I think in sheer political terms, the fact that Worth had made a succession of blunders and was trapped like a startled possum in the media spotlight would have been enough reason.

However, Labour and the media will argue that Worth was an elected (albeit on the party list) public office holder and the voters deserve to know what was the line in the sand that he supposedly crossed.

Usually a minister will lose his or her portfolio if under investigation or convicted of a criminal offence. In this case, Worth was not simply yellow-carded and made to sit on the backbench until it was cleared up; it was the red card and he was out of Parliament.

Another reason a minister will quit or be fired is if they have not told their leader the whole truth or misled him in some way. In the absence of any explanation from Key some people might now suspect that Worth misled Key and paid the price. Yet this may be entirely unfair. We don't know.

The Government's approach seems to be to "hold the line" and ignore the furore because, eventually, it will go away. The trouble is Key's desire to be reasonable. Despite his intention to say no more about his reasons for losing confidence in Worth, he keeps responding to the media interrogation and seems unable to draw a line under the question.

The best approach would be, simply to state: "I have nothing more to say on the matter. Any other questions on any other issues?" Muldoon, Lange, Bolger and Clark all quickly learned how to kill a question line. Key needs to do that, too.