For the child survivors of sexual assault and former students abused during their time at Sydney's Knox Grammar, Ms Perry's unflinching Royal Commission hearing testimony earlier this week certainly came as an extraordinary act.

With her trademark shock of pink hair making her an unmissable figure in the court, Ms Perry lobbed a grenade into proceedings when she claimed that she was sexually assaulted on stage during a musical rehearsal by the headmaster of Knox, Dr Ian Patterson.

Dr Paterson categorically denied the claim he had assaulted Ms Perry, even in the face of another former student testifying to having witnessed the assault.

Ms Perry's evidence earned a standing ovation from child sex-abuse victims and former Knox students attending proceedings.

She said it was "a very cool coincidence" that her evidence had been given in the lead up to International Women's Day, when she could stand up for her own rights as a woman - as well as the rights of all children - not to be sexually abused.

"I felt I had an obligation to tell the truth and I couldn't back away from that. When I heard the cheering outside court I realised what I was doing was so important to the survivors and I am so glad I could do that."

Ms Perry's sense of obligation and commitment to being a voice for the voiceless has included her bringing massive new awareness of, and almost $7 million in donations to, the work of legendary Australian Doctor Catherine Hamlin.

It is the reason she dyed her hair pink.

For the last 56 years, Dr Hamlin has dedicated herself to providing safe birth and maternal health services to the women of Ethiopia. Her most notable contribution was founding, with her husband, the Addis Ababa Fistula Hospital, which provides free obstetric fistula repair to women who have suffered horrific childbirth injuries when babies become stuck during labour.

Ms Perry, a mother of three who had successfully built her own communications firm in Sydney, saw Dr Hamlin featured on an Oprah Winfrey show had a profound reaction: "I basically decided to hunt her down and support her".

She took her camera and laptop to Ethiopia and began documenting the extraordinary work at the hospital, which has now treated more than 40,000 women.

Women who have not been treated for fistula are usually shunned from their communities, live in unsanitary conditions and sometimes die from their birth injuries.

Ms Perry said Dr Hamlin's love and reverence for her patients had such an impact she decided to commit herself to the cause. "She had me at 'hello'."

When Dr Hamlin, who is now 91, wondered how she could fund her ongoing legacy to the women of Ethiopia and keep her hospitals and midwife training school operational, Ms Perry stepped in as chief executive and established the charity on a business model.

The pink hair was a way to bring attention to the cause when Ms Perry was invited to meet movie star and human rights advocate Angelina Jolie during her Australian premier of Unbroken last November.

"Basically I wanted to get noticed. If I have to dye my hair a crazy colour for the women of Ethiopia then so be it."

With a dynamic speaking style and an innate flair for social media, Ms Perry has brought the work of Hamlin Fistula into the consciousness of countless Australians, who have donated $6.8 million to the cause over the last two years.

"International Women's Day hits me like a truck. I represent some of the most marginalised women in the world, but I do it coming from one of the most privileged countries in the world, and I am acutely aware of that contrast every step I take," Ms Perry said.

"Ethiopian women are just like Australian women. They want to have a fulfilling, enriched life with meaningful employment, and a happy, healthy family. They want to look good, be loved and accepted, with a little dash of awesome."

"The difference is we were born on the other side of the planet. Ethiopian women die waiting at the gates of hospital, women die in huts with babies dying inside their bodies when they become stuck in labour.

While Australia had access to 12,500 midwives with a population of 24 million, Ethiopia had less than 5000 qualified midwives with the population fast approaching 100 million. Part of the Hamlin Fistula mission is to train local midwives to attend to the women in their local area.

"Hamlin midwives have not had one maternal death in the field since deployment began in 2010. We recruit women from the rural areas [where] women are dying, we train local Ethiopian women to become skilled midwives. So it is a huge win-win - the sort that gives me goosebumps. Big International Women's Day Goosebumps!"