Image caption Sister Walburga used to be a social worker

Ask most people what they know about nuns, and many will have formed their impressions from the cinema: from The Sound of Music, to Philomena or The Magdalene Sisters, and Sister Act.

Those portrayals fail to offer much of a clue as to why the number of nuns joining convents in England and Wales is on the rise.

Recently, the Catholic Church said the number of women becoming nuns here had reached a 25-year high, with the number of women taking holy orders rising to 45 last year. Many are aged 30 or under.

That may not seem like many, but it stands in stark contrast to the global decline in women entering religious orders.

Figures in 2013 showed the number of nuns fell from a million worldwide in 1973 to just 710,000.

So what has been happening in Britain, and what makes women in the modern world choose to take vows of poverty, chastity and obedience?

Demystification

One reason may be the concerted effort by the Catholic Church here in recent years to demystify what nuns do, and to explain what life in monastic orders actually means.

Outreach and communication clearly help, but the Church believes there is something more profound going on.

Father Christopher Jamison, the former Abbot of the Benedictine Abbey at Worth, is the Catholic Church's national vocations director, and has overseen the revitalisation of its appeal to young people.

"There is a gap in the market for meaning in our culture," he says.

"Increasingly, young people find Christian faith filling that meaning gap, and for a smaller number of those, 'religious life' has a tremendous appeal because it leads them to the heart of human life today: to the heart of working for the poor, leading a balanced life and a great conviction that there is more to life."

The figures show a rise for enclosed or contemplative orders, as well as for active or apostolic ministry, and the work can vary immensely within both.

Some nuns in London can find themselves at the sharp end of social need in the modern world.

Some even accompany police on raids of brothels to help women who have been trafficked, while others work with the poor and the marginalised, or with elderly people.

Weekday order of prayers at St Mildred's Priory:

0530: Vigils

0830: Lauds

0900: Mass with Terce

1220: Midday Prayer

1800: Vespers

1950: Compline (followed by Adoration Monday, Tuesday, Thursday and Friday)

Those in enclosed orders are not completely cut off from the world, but they do devote themselves to contemplation and prayer, rising at 05:00 to start the day with vigils or matins at 05:30.

Former social worker

Sister Walburga, 35, became a Benedictine nun at St Mildred's Priory at Minster Abbey in Kent, where she leads a simple life as part of a small community.

She was a social worker who felt her calling to religious life grow stronger.

While she was thinking about her vocation, the Catholic Church offered her the chance to stay with the sisters there to see if it would be the right life for her.

"When my vocation really became strong, my boyfriend and I split up so I could explore it.

"My family thought I'd be locked away and miserable, but when they saw I was here and I was happy, they've come round," she says.

"Some of my friends were slightly bemused. One friend said to me that she didn't realise that nuns existed any more."

The rhythm of life is rather different for Roisin McGrogan, a novice with the Faithful Companions of Jesus in a convent in London.

Roisin is among the 27 women who joined active orders last year, working outside the convent, helping homeless and vulnerable people in the UK or abroad.

Internet app

Roisin, a 27-year old Irishwoman with an infectious smile, came to this ancient calling in a very modern way, using an internet web app to explore her options.

"Vision Vocation Match" allows would-be nuns to answer an internet questionnaire, to narrow down which religious order would suit them best.

Image caption Theodora Hawksley expects to flourish

Roisin agrees that it's a little like using an online dating site to find the perfect partner.

"I tried that too, but I found it less effective," she says, laughing.

"When you're looking for a life partner, or one love, it's to sustain you and to enable you to become the best person you can be ideally.

"And this is another way of falling in love: with great hope and great promise."

That is a feeling echoed by Theodora Hawksley, an equally engaging novice who was a theologian and academic, and is now writing a book on peace-building.

At the age of 29, she has become a novice with the Congregation of Jesus in north London.

Her work also involves helping homeless people, as well as taking part in the daily life of the convent, cooking and gardening.

Giving up a lot

I ask how she deals with the knowledge that she will no longer have the chance to marry or have children.

Her answer is direct and unhesitating.

"Yes, of course, that is going to hurt at various times. But in the same way as when you prune a plant, it encourages it to grow and flourish in different ways, that's ideally what should happen when you cut off one possibility of love.

"When you are chaste, other parts grow, and may be more flourishing, more welcoming to others.

"If our society is obsessed with money, sex and power and the games people play with them, then vows of poverty chastity and obedience represent a profound freedom.

"That's what has drawn me to religious life.

"It's not a fleeing from the world - it's a finding your place in it."

Whether a life of religious contemplation or participation in good works, both traditions of monasticism for Catholic women are clearly enjoying a fresh flourishing in Britain today.