So the Prime Minister is toughing this one out. John Key yesterday probably had little choice, however, but to stand by the Cabinet's appointment of Christine Rankin to the board of the Families Commission despite further questions about her suitability being raised by disturbing revelations about her private life carried in last Sunday's newspapers.

That Key was reluctant to discuss the revelations that Rankin married her fourth husband soon after his previous wife committed suicide was understandable. Doing so would have been to dive into a moral minefield.

As United Future's Peter Dunne says - and he has more of an axe to grind than anyone - Rankin is the wrong person to sit on the commission's board without delving into her private life.

Even if Key was to so delve, Rankin insists she was not having an affair with the woman's husband prior to the woman's death. Key has to take her at her word.

It may be easy to cast armchair judgments on Rankin's behaviour, especially if one makes assumptions about what happened. Ironically, those parties which welcomed her appointment, such as the Kiwi Party, may now be horrified by what has become public.

As far as National is concerned, however, Rankin's interview on TVNZ's Sunday programme injected shades of grey into a matter that had previously looked black and white. It is accordingly much more problematic for Key or anyone to make moral judgments in an official capacity, especially without full knowledge of the facts.

If Rankin's muddying of the waters made it more difficult to use morality as a valid rationale to justify her dismissal, the downside for the Government of her performance on Sunday was to pour more petrol on an already-raging bonfire.

But trying to extinguish the inferno by dumping Rankin now would have raised questions as to why she had not been dumped a week ago when Key says he first heard the rumours about her marriage, and even earlier when Social Development Minister Paula Bennett confronted Rankin on the same subject but did not tell Key.

The Prime Minister could hardly sack Rankin because the revelations had suddenly entered the public domain. Doing so would also have meant he was effectively reprimanding Bennett for not acting herself and for her failure to inform him she had talked to Rankin.

The Prime Minister may also have judged that it is not worth buying a public fight with Rankin, who is unlikely to have gone quietly.

On top of that, Key may also have decided National had already lost as much public goodwill as it is going to and retaining her services after the latest revelations is unlikely to cause any further political damage.

All that has to be balanced against the kudos Key would have received for admitting the Government had made a mistake by appointing her in the first place.

Still also in question is the damage this episode has done to the Families Commission's credibility, given most people will now assume the organisation is about to become a mouthpiece for Rankin.

To avoid that impression taking hold, Key yesterday stressed Rankin was only one of seven board members and that the role of board member was only a part-time one.

Most significantly, the Prime Minister finally put Rankin on notice, saying he wanted to hear her talk only about child abuse, her specialist subject and the supposed reason for her being on the commission's board, "and nothing else".

Too late. This horse has long bolted.