Dirty politics: Sex and smears, down under

For seven years, he has been the man married to the woman who runs New Zealand, an unassuming figure at Helen Clark's side as she claimed a succession of election victories.

Now Peter Davis has been thrust into the spotlight that he shuns, with the quietly spoken sociology professor at the centre of a political sleaze scandal engulfing both main parties.

Ms Clark was forced to take the extraordinary step last weekend of denying that her husband was gay, after photographs were published of Mr Davis being embraced and kissed by one of the couple's oldest friends, Ian Scott, an Auckland MP who is openly homosexual.

The Prime Minister said the clinch was entirely innocent - Dr Scott, who was "reasonably boisterous and drunk" at the time, was one of hundreds of supporters who attended her post-election party at Labour Party headquarters last year.

She made plain who she believed was behind the smear campaign: the opposition National Party, and its leader, Don Brash, who is fighting for his own political life amid allegations of an extramarital affair.

New Zealanders, unaccustomed to their politicians plumbing such depths, are riveted and horrified in equal measure. With no end to the muckraking in sight, Television New Zealand reported that "MPs across the political spectrum are calling on each other to pull back from the brink of what's being seen as a descent into the kind of tabloid exposure of politicians' personal lives seen in Britain and the United States".

One political scientist, Ray Miller, warned that "once you start down this slippery slope of sleaze and counter-sleaze, there are no winners".

While Mr Davis is the last person that New Zealanders would expect to see caught up in a gay sex storm, Mr Brash is an equally unlikely lothario. The 65-year-old was governor of the country's Reserve Bank before entering politics in 2002, and - despite revealing that he was a conscientious objector in his youth and demonstrated against visits by the South African rugby team - he has struggled to convince voters that he has much charisma.

That all changed last week after Mr Brash was challenged by one of his own MPs in relation to rumours circulating about an affair with a wealthy Auckland businesswoman, Diane Foreman. The National leader refused to confirm or deny it. But after the discussion was leaked to a newspaper, he took two days' leave, saying that he hoped to sort out "difficulties" in his marriage.

Things had already got dirty before then. For the previous few weeks, the Nationals had been accusing Labour, which has governed New Zealand since 1999, of misusing parliamentary funds in their campaign for last year's election. Two Labour MPs retaliated by making veiled threats to reveal details of the private lives of National MPs.

When Mr Brash rose in parliament to answer a question, he was taunted by one of Ms Clark's cabinet ministers, Trevor Mallard, who called out: "How's Diane this week?"

Mr Brash then mentioned the "Phillip Field affair", referring to a Labour MP alleged to have taken bribes in exchange for helping people with immigration applications. Mr Mallard interjected, loudly: "Speaking of affairs ..."

Ms Clark laughed off criticism of Mr Mallard. Until, that is, her own family became a target. On Sunday, after articles about her husband's sexuality had appeared, she said: "Trevor Mallard's behaviour was deplorable and should not be repeated. Trevor went off the deep end. I don't condone it. I condemn all those personal attacks."

The Prime Minister, a former academic sometimes accused of lacking passion, was in a cold fury after two mainstream newspapers, the Sunday Star-Times and Dominion Post, reported rumours about the relationship between Mr Davis and Dr Scott.

The articles appeared in advance of a report today in an offbeat current affairs magazine, Investigate, which has run a series of stories about Mr Davis and published the photograph of him being kissed by Dr Scott, who is a former Labour Party candidate.

Ms Clark said that the "vile, baseless lies" had been spread "quite cheerfully" by the National Party. She called on the Nationals to "call off the dogs", saying: "I cannot think of anything lower in public life."

While the National Party denied being behind the whispering campaign and even expressed sympathy for Ms Clark, she linked it to a lunch between Mr Brash and a gossip columnist with the Dominion Post, Bridget Saunders.

Ms Clark also claimed that a right-wing Christian sect, the Exclusive Brethren, was helping to spread the smear stories, accusing it of hiring private investigators to follow her and her husband around in an effort to dig up some scandal.

The Brethren, which funded a $500,000 (£180,000) pamphlet campaign in support of the Nationals at the last election, denied it. But as Mr Brash and his wife, Je Lan, appeared in public last night for the first time since news of his alleged affair broke, stepping out together at the launch of New Zealand Fashion Week, there were signs of more dirt to come.

Mr Brash had to call in police after files of his private e-mails were stolen from the parliamentary server, and several of his political opponents, including Ms Clark, have boasted about having a "book" full of them. Mr Brash has maintained that they contain nothing embarrassing, but described those who stole them as "the lowest form of scum".

The New Zealand media, meanwhile, has been dropping heavy hints that further revelations about the opposition leader's private life lie in store. Mr Brash said he was unconcerned, saying: "I haven't got anything else to hide."

Like Mr Brash, Mrs Foreman - who has fled to "one of her houses" in Port Douglas, Queensland - has refused to confirm an affair, but has not denied it either.

Mrs Foreman, who is married to a multimillionaire businessman and is deputy chair of an influential right-wing group, the Business Roundtable, told the Sunday edition of the New Zealand Herald that she had known Mr Brash and his wife for "a very long time".

"I make no secret of the fact that I have known the Brashes for many, many years," she said. "We have shared meals on many, many occasions, shared barbecues. I have had numerous dinners, lunches, breakfasts ... ah, maybe not breakfasts, with both Je Lan and Don."

Mrs Foreman insisted that her own marriage was "absolutely fine", saying: "I've got the most amazing husband, who is and continues to be hugely supportive." Her husband, Bill, their four children, and her parents put out a statement saying that they supported her and were "deeply offended and distressed" by the rumours.

The Herald on Sunday reported that the affair began when Mr Brash was still governor of the Reserve Bank, and said that he confessed to his wife when he realised that it was on the verge of being made public.

Mr Brash, who used to boast that he washed his own laundry in his hotel room basin during taxpayer-funded overseas trips on Reserve Bank duties, has been married to Je Lan for 17 years, and the couple have a teenage son. He began a relationship with her during his first marriage.

Mr Brash says he has no plans to stand down as opposition leader, and so far there appears to be no pressure for him to do so. Two opinion polls found that a majority of voters believe that he should stay on in the job.

However, support for him from senior figures in his party has been muted. His deputy, Gerry Brownlee, said: "I am deputy to Don Brash, and by virtue of that I express confidence in him, and I don't need to say any more than that".

The party's finance spokesman, John Key, and its former leader, Bill English, are regarded as the most likely leadership contenders.

For the moment, though, he is talking tough. He rejected a suggestion by Ms Clark that he would no longer be able to speak out on matters of integrity, replying: "Watch me." Asked about his own honesty, he said: "At no point have I misled the New Zealand public." Whether his marriage and career survive the storm remains to be seen.

Ms Clark, meanwhile, said wearily that she had experienced personal attacks throughout her 25 years in politics. "Political opponents have sought to defame me, and now they have sought to get at me through my husband," she said.

The main players

* Helen Clark: A tough-talking former academic who has been Prime Minister since November 1999 and leader of the Labour Party since 1993, following the party's electoral defeat. A keen concert-goer and supporter of the arts.

* Peter Davis: An internationally-recognised specialist in medical sociology who is head of the Sociology Department at Auckland University. He married Helen Clark in 1981. A photograph showing him kissing a gay former Labour Party candidate Ian Scott sparked rumours that Mr Davis is gay.

* Don Brash: The leader of the opposition National Party was accused of being behind the smear campaign. Mr Brash is a former governor of the New Zealand Reserve Bank who became a politician in 2002.

* Trevor Mallard: The Labour cabinet member challenged Mr Brash. Speaking in parliament, the Enterprise Minister asked Mr Brash about an alleged extra-marital relationship.

* Diane Foreman: A wealthy Auckland businesswoman. Mr Brash had already been confronted by his own party about the alleged relationship with Mrs Foreman, a family friend of the opposition leader.