Although she has been a member of Australia's Parliament for almost two decades, Ms Marise Payne, a law graduate and self- declared lifelong feminist, has long kept a low profile.

The 51-year-old is a moderate - or progressive - member of the Liberal party and has largely avoided the limelight, though she has never been afraid to speak her mind on issues such as Aboriginal rights or the need for greater engagement with Asia.

But all that changed last Monday with the historic swearing-in of Ms Payne as the nation's first female defence minister.

Her surprise promotion by new Prime Minister Malcolm Turnbull to one of the nation's most senior Cabinet posts put her firmly in the spotlight. She will be required to oversee the Australian Defence Force, which has attracted much negative publicity in recent years following a series of sex scandals and claims of a pervasive culture of sexism.

But her career would have taken a different turn if she had not been involved in a serious road crash as a late teenager.

She had grown up in and around Sydney and completed high school at one the city's most exclusive private girl schools, MLC Burwood.

At the time of the car crash, she was in university and planned to graduate, work as a barrister for some years and then enter politics.

But the crash, in which she almost broke her neck, convinced her to waste no time and go straight into politics.

"I think, if you want to do something, you should do it," she told a journalist in 1994. "Don't put it off, because you might not be around to do it."

So, after completing a combined arts and law degree at the University of New South Wales, she served as an adviser to numerous Liberal MPs and began her political ascent.

Neither of her parents was involved in politics, although she was close to both and has paid tribute to their support and guidance during her political career.

Her father was a World War II veteran who worked as an accountant and farmer. She once said of him: "He gave me every opportunity in life and, with his guidance, I have tried to make the most of them."

Indeed, Ms Payne quickly rose through the ranks of the Young Liberal movement and served as its first female president from 1989 to 1991. It took her several attempts to gain election as a senator, eventually winning in 1997.

She entered Parliament just as former MP Pauline Hanson was making headlines for her strident attacks on Asian immigration and multiculturalism. Ms Payne went further than many in the ruling coalition by attacking Ms Hanson directly, telling Parliament that Ms Hanson's One Nation party was "simply offensive, unacceptable and morally repugnant".

"There is no room, in my view, for the division and destruction wrought by hate-based race politics," she warned.

But her quiet career as a hard-working, little-known senator and frontbencher ended last week. Perhaps to the relief of both Ms Payne and Mr Turnbull, her surprise appointment was enthusiastically endorsed by the military establishment, which noted her extensive experience in defence and foreign affairs.

At her first press conference as minister last week, she asked to be judged "on my performance, not on my gender".

"If, as Australia's first female defence minister, I can encourage or that appointment encourages one extra young woman in this nation to consider a career in defence, to consider a career in politics, or encourages one woman currently serving… in what they are doing, then I think that is an absolutely fabulous thing," she said.

Given her feminist views, it would no doubt gall Ms Payne that - until her surprise appointment - she had perhaps received most attention in the tabloid media for being the partner of Mr Stuart Ayres, the New South Wales state tourism minister, who is 16 years younger than her. The relationship delighted the tabloids which broke the news of the couple in 2010 and described her as a "cougar". The couple live together in a newly built home on the outskirts of Sydney.

A former Liberal MP, Professor Russell Trood, an international affairs expert who served with Ms Payne on parliamentary foreign affairs and defence committees, said Ms Payne will be just as comfortable dealing with low-ranking privates and seamen as with generals and admirals.

"Marise doesn't seek publicity," he told The Straits Times. "She just wants to get on with the job - but sometimes getting on with the job brings you publicity."