Key Points:

John Key has a history of using luck and hard work to thrust his way to the top, a recipe he has used again to take over as National Party leader.

Throughout his life Mr Key has grabbed opportunities left open to him through vacancies or weak competition as well as being rewarded for his intelligence and achievements.

If his life remains on the course it has taken so far he could well be the next prime minister.

Today's opportunity arose after Don Brash resigned as leader on Thursday, before Nicky Hager's damning book was released on Friday.

Now at 45, Mr Key is one of the party's youngest leaders, although new deputy Bill English did hold the leadership before he was 40.

Mr Key's rags-to-riches story has been often told. He was raised by his Austrian-Jewish immigrant mother after his father died, leaving the family in debt.

A childhood in a Christchurch state house was a humble start but did not hold him back at Burnside High School then Canterbury University, where he graduated with a Bachelor of Commerce in 1982.

He subsequently studied management at Boston's prestigious Harvard University, in the United States.

His first job was project manager at Christchurch-based clothing manufacturer Lane Walker Rudkin for two years.

He then headed to Wellington to work for Elders Merchant Finance as a foreign exchange dealer, quickly rising to be head trader.

Head-hunted by Bankers Trust in Auckland, he stayed there for seven years before taking on head of foreign exchange for Merrill Lynch in London.

He also worked for Merrill Lynch in Singapore and Sydney and was a member of the Foreign Exchange Committee of the Federal Reserve Bank of New York.

After a successful career he returned to New Zealand a very wealthy man, with politics on his mind.

He settled into an $8 million mansion in Auckland with his wife Bronagh and their children Stephie and Max.

Mr Key had the midas touch in business and so far the same has happened in his political career.

Saunders and Unsworth's guide to the 2005 Parliament said Mr Key told his wife on their first date he wanted to be a National Party MP. He sent his Labourite mum a National rosette for a birthday present.

His rise through the ranks after winning the Helensville seat for National in 2002 was meteoric. By 2003 he was deputy finance spokesman. A year later he was finance spokesman.

He has raced up the ranks as well, from No 10 in 2002, to No 7 at the 2005 election.

He was promoted to No 4 by Dr Brash, in recognition of his skill at selling the party's tax package during the campaign.

Mr Key also kept the Helensville seat - with a 12,778 majority.

In recent polls he scored well - a New Zealand Herald poll of 750 Aucklanders showed Mr Key on 17.3 per cent support as preferred prime minister, just behind Dr Brash's 18.8 per cent.

Now he is leader - one, as former cabinet minister Richard Prebble once put it, straight out of central casting.

But pundits are already questioning whether he has the political depth to perform.

Such questions will make National a little nervous, especially in the wake of the Nicky Hager book that showed Dr Brash's inexperience hurt the party.

Lack of political nous tripped up Dr Brash, a man who was accomplished and confident in his former role as Reserve Bank Governor.

In previous roles Mr Key has pulled it off and his friendly, upfront manner has won him inroads with those who matter.

Hager's book revealed Mr Key annoyed both Mr English - his new deputy - and Dr Brash's deputy Gerry Brownlee.

He upset Mr English by promising to support him against Dr Brash but then voting the other way.

He riled Mr Brownlee by making his leadership desires public at a bad time for the party.

He now appeared to have managed to get back into the good books with both.

In the House he has performed well taking on political veteran Michael Cullen, sometimes winning, and seldom struggling amid the bruising argy bargy.

He speaks well and despite his wealth is down to earth and approachable.

Jewish, he goes to church but is "relaxed" about religion. He voted against civil union legislation in 2004 and voted for raising the age at which young people could buy alcohol.

He has a reputation for pragmatism and though some - such as Hager - say his more centrist approach is a front.

He fronted National's change of position on dumping the superannuation fund and on keeping Kiwibank.

Whatever job he has held he has turned into a success.

Now time will tell if he can make his mark on National.