I read an interview with Louise Redknapp explaining her reasons for leaving Jamie. Kind and loving as her husband is, she said, she felt she had lost her identity and become a Stepford wife; she said a mansion in Surrey and designer handbags couldn’t make up for that.

As I read, my thoughts turned to Lillian and the day we were sitting on the grass in the shade of a tree. We had met a few days earlier but her ebullient personality and honesty made me feel like we’d known each other for years as if we had grown up sharing teenage secrets. But we hadn’t. Our childhoods, our circumstances, could not have been more different. Because I grew up, like Louise Redknapp, with the privileges so many of us take for granted – education and freedom of choice – and Lillian, like millions of women all over the world, grew up with neither.

Lillian belongs to the Kuria tribe. Their lands span the border between Kenya and Tanzania and most survive as subsistence farmers. Lillian had a rudimentary primary education, but children growing up in Kuria country are expected to work. They rely on their small farms to provide all the food they need, so work takes priority over school. And then, when Kuria boys and girls reach their teens, they go through a rite of passage fundamental to Kuria culture: circumcision.

Female circumcision, or female genital mutilation (FGM), has been illegal in Kenya since 2011. It’s a practice that has absolutely no medical benefits, but carries with it the risk of terrible complications and even death. The UN describes it as “a violation of the human rights of girls and women”, but, as I discovered, ending a practice that is so deeply rooted in a culture takes more than laws.

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Kate Humble in Kenya (BBC, TL)
Kate Humble in Kenya (BBC, TL)

Lillian held my hand as she talked about what happened to her and hundreds of other girls who were circumcised alongside her. She described the fear, the extraordinary pain, but also the excitement because with one cut of a blade a girl becomes a woman in the eyes of her community. She is marriageable. For the first and perhaps only time in her life she will feel she has value. Because when it comes to marriage in Kenya, brides are paid for. Lillian’s parents were offered 14 cows for her, a price they were not prepared to refuse, even though it was committing their daughter to a life she didn’t want.

The person who paid to marry Lillian wasn’t a man, but a woman called Pauline. She was the first wife of Masenda, who, as is normal in polygamous Kuria society, has three other wives. Pauline had given birth to two sons, but both had died. Now too old to bear children, she “bought” Lillian to work for her as a daughter-in-law might, but mainly to provide her with offspring – ideally boys, who, in this patriarchal world, would work the land and then inherit it.

So, I asked Lillian, was Masenda the father of the two boys and two girls she has subsequently given birth to? She shrieked with laughter. “No! It is easy to find someone to have sex with. My children all have different fathers.”

“And do you get any financial help from the fathers?” She looked at me as if I was mad. “My life is hard because I have no financial help,” she said, “no husband to support me. I have to earn money to feed, clothe and educate my children, as well as look after Pauline and her house. I work on someone else’s farm.”

“How much do you get paid?” “200 shillings a day.”

That’s less than £1.50.

This series was one of the most complex and illuminating I have ever undertaken. My understanding of what I believe to be right and wrong was challenged at every turn. But it was Lillian who proved that when you are robbed of education and any chance to better your life, you are also robbed of another basic human right. Choice.

She gripped my hand, her eyes tearful. “My daughters must not have the life I have had. I do not want them to be circumcised. I will kill myself if I can’t give them an education.”

Extreme Wives with Kate Humble is on Friday 9pm BBC2 (Sat 11 Nov in Wales)