They aren't nuns, but they do choose to remain celibate for their whole lives; around 3,500 Catholic women worldwide are known as 'consecrated virgins'.

While nuns take an oath and join a religious order, consecrated virgins instead live out their calling outside the walls of a convent. The journey begins with a ceremony that does not include vows of poverty or obedience, but the woman in question does wear white, and receives a ring and a veil to represent her marriage to Christ. They believe they are echoing Jesus' words in the Gospel of Matthew that some "choose to live like eunuchs for the sake of the kingdom of heaven".

It is a long-held tradition in the Catholic Church, which believes Mary was the first sacred virgin, but the practice gradually declined during the Middle Ages. However the ceremony, known as the Rite of Consecration to a Life of Virginity for Women Living in the World, was revived by Pope Paul VI in 1970. There is now a US Association of Consecrated Virgins, the president of which, Judith Stegman, estimates that there are 230 women in the States who have committed to the lifestyle.

Elizabeth Bailey was the first woman to be consecrated in England since the third century in 1972. She told the Independent in 1996 that her chosen path is "quite exciting".

"It is a totally different way of life and it's a perfectly reasonable and happy life," she said. "Yes, contented."

Advice on the Diocese of Shrewsbury's website says: "Christ calls certain women to live 'for the sake of the Kingdom of heaven' (Matthew 19:12) as consecrated virgins. This has been so ever since the earliest days of the Church, when such women, along with widows, could serve the Lord with a great freedom of heart, body and spirit."

Once consecrated, the woman has "the grace of manifesting the love of the Church, the Bride for her Bridegroom Christ, and the grace of foreshadowing the heavenly wedding feast of the Christ and the Church," the website continues.

"The consecration of the virgin is a sacramental, with the nature of a lasting perpetual identity of a Bride of Christ. The consecrated virgin holds a spousal relationship with Christ reflecting the spousal relationship between the Church and Christ."

The life of a consecrated virgin may seem sacrificial, but Bailey insisted that it never felt that she was giving anything up. "I felt I was receiving something. I think virginity is a gift. I don't think it's suffering. It's a way of life in itself. The whole person is involved," she explained.

"There are things that one would find difficult. The life is not easy because it can be quite lonely. But if you want something, you go for it, don't you?"

Seeing the unusual lifestyle as a gift is something that Shelia Ryan, the latest woman to become a consecrated virgin in Richland, Pennsylvania, last Sunday, also resonates with. "I knew as a teenager that I was not called to the married state," she told the Pittsburgh Post-Gazette. "It's listening to God and being open to his workings of grace within us. Nobody would seek this life, which is counter-cultural, unless it were a gift from God. And I consider it a gift."

Ryan hadn't heard of consecrated virginity until 2009, after which she asked Bishop of Pittsburgh, David Zubik, if he would bless her into the lifestyle. He agreed, and Ryan then spent two years preparing ahead of the ceremony. Zubik told the Post-Gazette that the Church should "provide as many opportunities as we can to help people on the road to holiness".

"There's not many people called to it, [but] it's a legitimate option in the Church," he added.

In a separate interview with the National Catholic Register, Zubik said that every Christian has a responsibility to demonstrate their pursuit of God in the way that they live, whether they are married or single. Consecrated virgins in paarticular are "very much committed to a life of prayer", he said, which "adds to the vibrancy of the Church".

In a post-Christian culture, the idea of living a celibate life is certainly unconventional and Ryan admits that "some people may cringe" at the thought. "So often our culture doesn't use the word 'virgin' in a serious way, or makes fun of it," she says, but insists that consecrated virgins are "very serious".

"The woman is drawn to a love relationship to Jesus that is most fulfilled by giving herself entirely for him."