In 1988, Ann Cotton decided to leave her job as an English teacher at a Cambridgeshire secondary school and move to the US city of Boston with her husband, who had been transferred to a new job. But the flight to Massachusetts did not mark the end of her career in education: it triggered a chain of events that led to her embarking on a one-woman odyssey that has changed the lives of millions of girls in sub-Saharan Africa.
Ms Cotton's extraordinary journey has culminated in her being presented with a prestigious international award dubbed the unofficial Nobel Prize for education. At the World Innovation Summit for Education (Wise) in Qatar this week, the founder of Camfed (Campaign for Female Education) was named the 2014 Wise Prize for Education Laureate.
The title, which comes with a $500,000 prize, was awarded in recognition of Camfed's work over the past two decades in Ghana, Malawi, Tanzania, Zambia and Zimbabwe.
But the story began when the mother of three enrolled on a course at Boston University. This ignited her passion for research, and when the family returned to the UK Ms Cotton enrolled on an MA in human rights and education at the University of London's Institute of Education.
She wanted to understand exactly why girls in many African villages were missing out on schooling. According to the conventional wisdom of the time, the reason was cultural: parents were simply not prepared to allow their daughters into the classroom.
But a visit to Zimbabwe showed Ms Cotton that this was not the true picture. "Parents told me, `We want all our children to go to school but we can't afford it. We support boys because they have a better chance of paid work in the future.' It was about family poverty rather than resistance to education," she said.
The answer, she quickly realised, was to help families to adapt. Few in the international development community agreed, however. So, despite being offered the chance to study for a PhD at the University of Cambridge, Ms Cotton decided to press ahead with her search for a solution to the problem of girls' schooling. And in 1993, Camfed was born.
"I realised that if you met the costs of education for girls then they could go to school," Ms Cotton told TES.
Today, Camfed offers financial support to African girls for everything from shoes to school fees, and helps families to understand how to support their daughters - for example, reducing the burden of chores in order to give girls time to complete their homework.
"It's not that they don't care. They just don't understand how they can support their children better," Ms Cotton said. "They don't know what the marks in the school books represent. Once you teach them a tick is good and a cross is less good, they start looking and getting quite excited about their children's work."
The support also extends beyond the family unit. Camfed trains mentors for girls in more than 5,000 schools and sets up community development committees to ensure that local officials are on board. The organisation has also built an alumni network of more than 24,000 young women who have come through the programme, who support and tutor the next generation of girls in their communities.
The consequences of the project - including reducing birth rates, child marriages and the spread of HIV - have been transformational. Not surprisingly, Camfed's work has attracted plaudits from across the globe. "Ann Cotton has dedicated her life to improving the education of girls and the empowerment of young women in sub-Saharan Africa," said Sheikh Abdulla bin Ali Al-Thani, chairman of Wise.
British prime minister David Cameron said he could not think of a "more worthy winner of this prestigious award", adding: "The scale and impact of the work she has done through Camfed to educate millions of girls and young women in Africa is simply remarkable."
Ann Cotton CV
1950 Born in Cardiff.
1970s-80s At the age of 20, she began teaching at a London girls' school, where she established a centre for girls excluded from mainstream education. She also taught at a Cambridgeshire secondary.
1988 Moved to Boston. After researching the Massachusetts education system, she returned to the UK to study for an MA in human rights and education at the University of London's Institute of Education.
1993 Founded Camfed.
2004 Named UK social entrepreneur of the year.
2006 Appointed OBE for services to girls' education in Africa.
2007 Awarded an honorary doctorate from the University of Cambridge.