New Zealand's new Prime Minister, John Key, 47, who steered his conservative National Party to victory in Saturday's general election, is a classic example of a poor boy made good.

Brought up by his mother in a state house after his alcoholic father died when he was seven, he made a fortune overseas as a foreign currency dealer before returning home to enter parliament a multi-millionaire and its richest member.

He credits his success to his Jewish mother, an Austrian who fled Vienna in 1939 and worked as a cleaner to get him through university, after rejecting advice to declare bankruptcy to avoid the debts her husband left behind.

Key has had a meteoric rise to the top with just six years in parliament and will be the most inexperienced prime minister in over a century.

Shrugging off taunts by Labour's acerbic former finance minister Michael Cullen, who called him "a rich prick," the softly spoken Key has maintained a somewhat bland "nice guy" image in parliament.

He has confessed that even when he had to help sack 500 staff as part of a savage worldwide retrenchment by the Merrill Lynch bank he did it in such a way that they called him "the smiling assassin."

Married with two children, Key was fascinated by politics as a boy but was determined to make a lot of money first so that he could be financially independent.

That money has allowed him to buy two multi-million dollar homes in Auckland (residence and weekend cottage), one in Hawaii and an apartment in London - not the usual property portfolio of a New Zealand politician.

Key's opponents have dubbed him "slippery" for a series of policy flip flops which they said indicated a lack of political conviction, leaving them not knowing what he actually stands for.

He unwittingly fostered this belief when he said that he had held "no strong view" about the all-white South African rugby tour of New Zealand in 1981 - an explosive issue that bitterly divided his multi-racial country, provoking battles in the streets.

Key admits to changing his mind on some issues - including reversing a 2003 opinion that New Zealand should have joined the US-led invasion of Iraq. "The fact that I'm in tune with public opinion doesn't mean that I'm slippery," he says.

Throughout the election campaign Labour painted Key as an impassive front man for radical right-wingers in his National Party who were using him to reassure an electorate suspicious of extreme conservative policies.

As he deliberately moved his party to the centre after taking over the leadership two years ago, he was attacked as a closet Socialist by the right wing ACT party, who favour slashing welfare in favour of self-reliance.

Although his party's manifesto reflects conservative policies like tax cuts, reduced government spending and greater use of the private sector, Key paints himself as a compassionate pragmatist.

"There will always be a social welfare system in New Zealand because you can measure a society by how it looks after its most vulnerable," he says. "Once, I was one of them. I will never turn my back on that."