Often referred to as the 'real-life Call the Midwife', Eleanor Stewart has led an unusual life. She spent eight years of her early adulthood as a nun; first in the French convent of the Sisters of Charity of Our Lady of Evron, and later in 1960s Liverpool. But initially drawn to the chaste life under the illusion of adventure and romance, working as a midwife left her doubting the decision to give up the one thing she found she craved: motherhood.

"I thought it was very romantic to tell the truth; giving up everything for God. How romantic is that? Giving up everything for love! That is so adventurous, so courageous...you're doing something very extraordinary for God," she told Christian Today.

"There are so many things in the Bible that call you to that – "I know you by name," "You belong to me," this idea that once God's got his claws into you, he's not going to let you go.

"Francis Thompson, the poet, saw that amazingly. He felt he was being "pursued by the hound of heaven," no matter what he did those "strong feet followed, followed after", and I certainly felt that. I felt that I couldn't put it down until I'd tried it."

After spending three years in France, Stewart was moved to Liverpool where she trained as a nurse, and later a midwife. Far from hanging out at popular haunts for those of her age like the Cavern Club and the Pink Parrot, she split her time between the convent, the hospital and the homes of pregnant women in some of the most disadvantaged areas of the city. By now in her mid-twenties, however, she realised that she wanted to have children herself and began to question her vocation.

"I began to feel strongly that the maternal instinct was becoming pretty insistent," she recalls. "I was told that was very normal, but you're being tested and have to make a choice. I didn't know what to do." Eventually, she asked for a dispensation, and left the order.

It was a tough decision, but Stewart says she was never given a hard time about it by the other sisters. "They were very supportive, very lovely...It was harder to leave than it was to go in," she says.

"When you go in [to the convent] it's a wonderful new adventure, you're giving your life to God, and when you leave you don't know what you'll be facing. You're leaving a loving community...you're leaving your family."

And England in 1968, when she left the convent aged 26, looked very different to how it had eight years earlier.

"There was this sudden explosion of flower-power and young people and the development of 'do your own thing, be who you are'...That was heavy stuff for somebody coming out of a convent," Stewart says.

By her own admission, she threw herself headlong into this exotic new life. "I had never had a bank account, a chequebook, paid a bill, or handled money...It was all completely new – an explosion of excitement and experience, and I really lost my head for a bit." She was so completely unaware of how to handle herself that her new flatmates were relieved when she eventually admitted to having been a nun. "They thought I'd been in prison".

But not everything went to plan. Stewart contracted chlamydia through a partner, which eventually led to her infertility, and once married she discovered she would never be able to have her own children. She and her husband, John, then adopted two children, Esme and Paul. The process was gruelling.

"On one occasion I remember somebody saying 'You do realise, don't you, that most children who are adopted are from unmarried mothers? If you have a 15-year-old girl who you feel is out of control and probably running around with boys doing things she oughtn't to, will you feel she is taking after her natural mother?'" she says.

"John leaned back in his chair, yawned and stretched, and said: 'Not at all. I shall think she's taking after her adoptive mother.'"

Now aged 72, Stewart looks back at her time in the convent with fondness. Does it seem like another life?

"It doesn't, that's the strange thing, it doesn't seem like another world and I dream about it often. I have this vivid dream when I'm having to make the choice all over again. But part of me longs to go back, isn't that strange?

"I don't regret leaving, but those eight years I think were probably the most significant years of my young life. I think my moral compass and my view of how I ought to be as a good citizen in this world was shaped then, and even my political view I think comes from that."

She describes herself as a believing Catholic, not a practising one, with "a deep, everlasting devotion to the Virgin Mary".

"I still pray...I do count myself as a strong, fervent believer, it's just a different way of living it out," she says.

"I don't think God ever, ever lets you go."

New Habits, published by Lion Hudson, is available to buy now.