In the centre of England's capital there is a convent of nuns who never step outside the walls. But they are not untouched by London's life, or its deadly bombings.
Nuns wear a white cowl for their seven daily prayer services
It is before sunrise and London has yet to wake up to a misty summer dawn, straight out of a Whistler painting.
But behind the locked doors of a city-centre convent, a dozen Benedictine nuns are already chanting prayers in the first of a series of daily services.
One note, Fa, rings out on the glockenspiel as they sing psalms and listen to Bible readings.
Those are the only noises at 5.30am, in the white, arching chapel at Tyburn Convent, a cloistered community of contemplative nuns, whose job it is to pray.
Obedience (to the order's rules)
Stability (to the congregation)
Conversion of life (including chastity and poverty)
It is so quiet that the sounds of shifting in your seat, focusing a camera, flipping-over a notebook page are magnified.
Tyburn sits at the top of Hyde Park, by Marble Arch, a public execution site from 1196 to 1783. During the Reformation, from 1535 to 1681, 105 Catholics were hanged - and sometimes drawn and quartered - on the Tyburn Tree gallows.
Frenchwoman Marie Adele Garnier founded the convent in 1901. Relics of bones and clothing from Tyburn's Catholic martyrs remain downstairs in the crypt.
It is steps away from the capital's busiest shopping strip, Oxford Street. Yet the 26 nuns do not set foot outside.
"Unless you have to go to the doctors, dentist, for banking business or to book travel," says Mother Lioba, 50.
Travel, that is, only to one of the order's other houses abroad.
Otherwise, not even a holiday to the Vatican would be considered. Although, smiles Mother Marion, 32, "If the Holy Father asked us, I suppose we would have to go."
The three linked buildings house a chapel, the nuns' cells, a library, kitchen, refectory, chapter and surround a high-walled garden. Food and other essentials are delivered in.
It is a structured day of study and work for the convent, worked around seven services. Plus, a Mass, open to the public who worship out of sight, behind a grill.
Executions took place at Tyburn from 1196 to 1783
The nuns wear the traditional habit. After final vows are taken, that means a black veil, white guimpe around the neck, full-length habit, white cowl (cloak) during services, medal, ring and rosary.
They are not the apostolic nuns, who go out to teach or to nurse in a life of charity. There is someone praying in the chapel even in the dead of night.
So who joins a religious order in the 21st Century? In the Catholic Church in England and Wales, just three women entered enclosed orders (like Tyburn) in 2004, and 10 apostolic.
Sisters sometimes quit their order and, although it is a serious decision, it involves letters to the Vatican rather than excommunication.
Nuns' novelty factor is played up in the popular image - the karate black-belt nun from Norfolk; the statue-carrying Sister who visits pubs and supermarkets in Sussex.
And there are preconceptions about the severity of convent life. Mother Marion recounts a phone conversation with her mother shortly after she came in. While chatting, she noticed a cupboard was open.
"I said to her (my mum), hang on I'll just go and shut the cupboard door. She said, 'What! You are in a cupboard?'."
But Tyburn has 24 sisters in the long process of becoming nuns - through 'living in' with the order, postulancy, as a novice, taking first and final vows. They have many nationalities and live in the order's eight houses worldwide.
There are senior members - Mother Odilia is 96 - but the congregation looks younger than expected. Sister Catherine is 23, the average age at Tyburn, says Mother Lioba, is under 40.
All say they were called by God.
For Mother Lioba, that came when she was 35, on a visit to see her sister, Mother Gregory, also a Tyburn nun.
"As I grew older, there was a definite attraction to the cloistered life. You have to have the kind of mentality to be enclosed," she explains.
STAGES TO BECOMING A NUN
Contact the order/Mother Prioress
Living in (several weeks)
Postulancy (6-12 months)
Noviciate stage (1-2 years)
First profession of vows to be a 'junior'(3 years)
Second, or Monastic profession
Whole process: about 5-9 years
"I walked into the chapel and I thought I was going to end up there."
The response, is she says, "almost a romantic response, a real love response - 'can you live without this?' And you live that out within a community."
Tyburn is at the end of a shoppers' paradise, opposite a fine park, in one of the greatest cities. Nuns are allowed only 1 1/2 hours of personal visits a month, so do they feel trapped?
"You get used to it," says Mother Marion. "You can be called to be a nun, but not a contemplative - some people come and they immediately feel 'Let me out!'
"At first it's really hard; you miss your friends and family, taking the dog for a walk. But after a while, this is your home, this is what you are doing and you are just at peace.
Mother Lioba, sent to Ecuador to establish a new monastery, says the enclosed life gives her more freedom.
"I'm a timid person," she says. "I'd never have done half the things I have, given the choice. My own limitations would have prevented me.
Prayer requests come in by e-mail
"You leave it in God's hands, If they say you go, then you do it. I'm a lot more free to be myself as a human person.
It seems naïve to think of the Tyburn nuns as isolated by their work and situation.
They may listen to the radio only rarely - "papal funerals and accessions. Royal weddings, of the solemn sort".
But there are popular works on the library shelves - "Lord of the Rings; book with a resurrection theme".
Power of prayer
Catholic papers and the Weekly Guardian are delivered. "If you have no contact other than a weekly paper, it's amazing what you can learn about the world from that," says Mother Lioba.
When the London bombers struck, the convent's lay helpers phoned to alert them, a daily paper was sent for.
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But above all it seems to be the letters and e-mailed prayer requests, posted on the walls, that keep them in touch.
"One of the older mothers is still in shock that people did this in her London," Mother Lioba says of the attacks.
"Even though we weren't out there, we feel an empathy with the people. For us, prayer is a personal involvement, we stand there before God for those people. We share the suffering of the world, we take them into our prayers.
"If you didn't believe that there's a God and prayer is talking to him, you'd say prayer wastes five hours a day.
"But I don't think either of those things."
"The thing that really surprises me is that we get letters back that say 'we could tell you were praying'. We weren't just doing it in isolation."