Albert David is on his own in the office when the phone call comes. “I’m calling from a restaurant toilet,” the voice whispers. It is a female voice, and a young one. Young, quiet and afraid.

“I can’t talk any louder than this - they might hear me. If my family finds out .” There is a pause. “My father has a rifle,” the whisper says, and it quivers and catches. “He could shoot me. Really, he could shoot me. I’m . I’m .” - there is another pause, a muffled, swallowed sob - “so scared”.

Albert David is head of the assistance unit at the British High Commission in Pakistan. Heart-wrenching calls from school-age victims of forced marriages are a routine part of his day’s work. On average, he receives two new phone calls a week.

“It’s OK,” he answers, his voice all calm reassurance and capability. “I’m here to help.” Will there be less chance of the girl’s family catching her if they communicate by text message instead of phone call, he asks? The voice doesn’t answer immediately, but when it does, it speaks with palpable relief. “Yes. Yes, please. Thank you.”

This is a quiet day. Busy days are different. Not long beforehand, two members of Mr David’s four-strong team had been on a rescue to a remote village when they realised they were being followed. The cars pulled ahead of them, forcing them to stop. There were two policemen in the rescue convoy, and they climbed out. Their pursuers stepped out too, and they were armed. For a moment everyone stood still in the chill mountain air, the silence pulsing between them. In the rescue car, a teenage girl shrank into the upholstery while the police talked the gunmen into letting them pass.

There are no rescues today. By the time Mr David’s colleagues arrive into work, the new case has been carefully documented and the girl’s name added to 23 open cases - five boys, 18 girls - listed on the whiteboard in the unit’s office.

Behind a heavy metal gate, the High Commission in Islamabad is a small corner of England in a foreign land. In a city of dust and dried grass, the vivid green of its lawn is striking: the neatly tamed borders are a valiant piece of the home counties under incongruous tropical sun.

Mr David’s assistance unit occupies a long, thin office, its walls papered with dog-eared maps and posters. The civil service desks, thick with paper and files, betray little of the department’s action-adventure nature: this is the team that helped investigate the case of Sahil Saeed, the five- year-old boy kidnapped in March, while visiting relatives in the Punjabi city of Jhelum, about 65 miles south of Islamabad. But kidnappings are relatively rare. Two-thirds of the calls received by the unit concern forced marriages, British school pupils and young adults whose parents attempt to coerce or compel them into marriage in Pakistan.

The reality of forced marriages lies buried under a layer of myth and preconception as thick as the departmental paperwork. Forced marriages are not commonplace throughout Pakistan: they are restricted to very specific cultures and contexts. Sixty per cent of cases the office deals with are concentrated in the Kashmiri cities of Bhimber, Mirpur and Kotli, where strong family connections are valued, and children often expected to marry first cousins.

Families from these areas have moved to Britain in large numbers, bringing their cultural expectations with them. In some cases, British-Pakistani teenagers end up in relationships with fellow British-Pakistanis from the same region of Kashmir, even from the right family in the right town in the right province. But if parents have decided that their child should marry one particular cousin in Pakistan, only that specific marriage will be acceptable. Levels of education make little difference. Culture, like religion, transcends the rational.

By mid-morning, Mr David has exchanged several text messages with the terrified girl in the bathroom and work on the case has begun. Around him, his staff are also phoning, texting and documenting. “People can be really, really torn between two worlds,” says Jason Doondeea, the vice- consul.

Mr Doondeea’s accent is unmistakably London, but he is of Mauritian heritage and has first-hand experience of the strong family ties of the subcontinent. As teenagers, he says, many of his friends kept burgeoning relationships secret from their parents, torn between conflicting British and Asian identities. “There is a strong sense of love, of respect and loyalty to families. But you are brought up in Britain. So there is a tremendous amount of pressure.”

Often, it is not the victims themselves who contact the unit. A series of awareness-raising campaigns in Britain has had a significant impact, and concerned friends and relatives will get in touch on behalf of a victim. Teachers regularly contact the office when pupils do not return to the classroom after a holiday.

Last year, the Foreign Office issued new guidance for schools, urging them to play a greater role in identifying the signs of forced marriage. A report from the government’s Forced Marriage Unit (FMU) said schools were often reluctant to get involved in what they perceived to be a cultural issue. The FMU received 770 calls in the first six months of last year, an increase of 16 per cent on the previous year.

Phone calls tend to peak during and just after the school holidays: this is when parents are able to take their children away. Between April 2009 and March 2010, the assistance unit in Islamabad dealt with 121 cases; there were 124 the preceding year. In August 2008, 22 new cases were taken on by the unit: the equivalent to one every working day.

Inevitably, there are also false alarms, often from bitter ex-boyfriends who assume that a forthcoming marriage must be forced. “Remember when we had to travel three and a half hours through the hills?” says consular officer Zainab Ikram. “We found out that, yes, the girl had got married. But she had known about it in advance, and it was completely consensual.”

After his initial contact, Mr David has passed the latest case on to Ms Ikram, and she is now attempting to establish basic details via text messages. The first message in such cases is inevitably innocuous - “Hi, how are you?” - purely to see if a reply is forthcoming. The key is to obtain as much information as possible in as safe a manner as possible.

Wherever practical, officers ask victims to come to the High Commission. Families are given bland excuses in bureaucracy-speak: “It’s just a routine policy check, something that can’t be done over the phone.” Potential victims are then taken aside and interviewed on their own, where it is hoped they will be able to speak more freely.

In many cases, though, families will not come to the commission (“We are not the ones with the concerns,” they say. “Why should we go out of our way?”) And so the commission must come to them.

Ms Ikram has now established the necessary contact details for the scared girl in the bathroom. “The address is vital,” she says. “If you have no address, or the address is only incomplete, it can make things so, so difficult.” Many of the calls come from remote areas. Without the name of a village and a head of household, consul staff could be roaming fruitlessly through remote mountain villages.

At the desk opposite, fellow consular officer Neelam Farooq is studying a map of Pakistan on the wall. Underneath, a more detailed map highlights the contours of Kashmir. “There was one case, where the girl asked us to meet her in this graveyard, at this time,” she says. “She said, `Don’t come to my house’. And the only way she was contacting us was by picking up whatever phone was lying around.

“But we couldn’t find the village. She could have been out there, standing anywhere. I really felt scared for her. What can you do, except hope and pray she will contact us again?”

This is not hyperbole. In many cases, the threats to the victim are very real. On one occasion, Ms Farooq was halfway back to Islamabad after a rescue, when the girl fished a handful of bullets out of her bag. Her father had threatened her with a pistol, insisting that she go through with the marriage. She had thought it judicious to remove the bullets.

In her texts to the girl, Ms Ikram is now trying to establish whether there is the possibility of violence or if there have been threats to the girl’s life. This can dictate how urgently staff approach the case.

On average, consular officials will conduct between two and four rescue visits every month. For their own safety, they are always accompanied by two policemen. So Ms Ikram is also attempting to ascertain how influential the girl’s family is and what their relationship is with the local police.

Visible police presence aside, the conversation that goes on at the family home is typically British in its studied formality. Staff will begin by saying that they have received information from relatives in Britain - they will never implicate the victim - and want to check on their son or daughter’s welfare.

They refuse to leave until they have spoken to the victim in private. Victims are then presented with their options: they can stay with their families and go through with the marriage, or they can come with High Commission staff. They can, of course, choose to stay now and change their mind at a later date. But they should be aware that families often respond to a High Commission visit by bringing the wedding forwards or moving the victim to a new, unknown location. This may be their last chance.

Many victims now opt to leave with the commission staff. Again, the conversation with the family is terse and to-the-point: “Your child has asked for our assistance to return to the UK. Any further contact should be through the High Commission.”

When victims are under the age of 16, staff must obtain a forced-marriage protection order from a British court before embarking on the rescue. This takes 24 hours to secure and enables them to take children away from their families without fear of reprisal.

But while officials hide behind legal formality, families often seek refuge in melodrama. “The situation is emotionally charged,” says Ms Farooq. “The first case I did, the grandmother grabbed hold of my feet and yelled, `You can’t do this!’” Ms Ikram nods. “Yeah, one mother grabbed my arms and was screaming at the top of her voice. You couldn’t make any sense of her - we just had to pull ourselves away and leave.”

Fathers, meanwhile, have their own brand of guilt-inducing melodrama. Some accuse the departing victim of bringing irreversible shame on the family. Others threaten to divorce their wife - their children’s mother - unless the marriage goes through. With disturbing regularity, families call the High Commission and report a paternal heart attack. This news is thoroughly investigated by staff before being conveyed to the victims.

On only one occasion was the report actually true: the father had died the day after the rescue. “The girl went back to her family,” says Ms Ikram. “She was blamed for it, obviously. That guilt will probably be with her for the rest of her life.”

And then there is the violence. On one recent rescue, Ms Farooq was surrounded by angry villagers as soon as she stepped out of the car; her colleague was prevented from leaving the car at all. Outnumbered and on her own, there was nothing she could do but wait. “Luckily, there was a back door,” she says, fiddling with her scarf. “The victim knew we were coming, so she ran out and got into the other car. We were very lucky - there was a huge crowd there, and it was impossible to control them.”

Occasionally, however, the act of intervention can be enough to make parents realise what they are doing. Recently, as a girl was about to leave with High Commission staff, her emotional father ran for a copy of the Koran. “Don’t do this to us,” he said. “I swear on the Koran that I will allow my daughter to marry whoever she wants, if she will just” - here he looked his daughter in the eye - “stay, please.”

Ms Ikram was conducting the rescue. She moved between the man and his daughter and gazed coolly back at him. “I’m a Muslim,” she told him. “You’re also a Muslim. I hope you understand the sanctity of putting your hand on our holiest book and making a promise. And I hope you will keep it.”

In most cases, however, staff will not intervene in family conflicts. Their role, they reiterate repeatedly, is not as counsellors or mediators. “We say, `You have asked for help, and we are here to help you’,” says Mr Doondeea. “Sometimes victims want us to reason with their parents, mediate with them, threaten them. We can’t do that. And we can’t negotiate terms of marriage for the guy she actually wants to be with. That’s not our role. If a British national needs assistance being repatriated to the UK, that’s our role.”

The boundaries are distinct in other ways. Texting the girl in the bathroom, Ms Ikram has a strict bureaucratic hurdle to clear before she can go ahead with the rescue: the girl must say clearly and explicitly that she gives her consent for staff to come to her family’s house. And willingness to be rescued must be stated - either by the victim or by her rescuers - in front of her family. “The police have to be sure that we are not abducting someone,” says Mr David. “One case going wrong could jeopardise everything we do.”

Once in Islamabad, rescued girls are housed in a domestic-violence shelter until they can be repatriated. Boys stay in a local guesthouse. Then comes the hard part.

Back in Britain, nothing is going to be the same again. The assistance unit works with the FMU in London, ensuring that victims are met at the airport by friends, family members or a sympathetic teacher, and that accommodation has been arranged in a shelter. Victims then face the debris that was once their life: they must make their own way, without any family support.

Unsurprisingly, some victims decide to go back. Alone in Britain, an undesired marriage can appear the lesser of two evils. One boy had been close to his parents, and struggled with his new isolation. Within a week, he had returned to Pakistan. But, back in Pakistan and confronted with the situation they have escaped once already, victims will sometimes change their mind again. “We rescued one girl three times,” says Ms Ikram.

She is now conducting essential checks on the girl in the bathroom. The unit must establish unequivocally that the victim is a British national before embarking on a rescue. But, as arrangements for the drive into the hills are finalised, she has no idea how the case will end. “They are under enormous pressure,” she says. “It is not easy to stand against your family, to stand up and say, `This is what I want’, then have them wash their hands of you.”

Mr David nods in agreement. “We have had several cases where you can see from their eyes that they need help, need to be rescued, but their words are saying something completely different,” he says. There is no hint of weariness in his voice. This, like the violence, the false alarms and the sudden severing of contact, is just another part of the job.

*Some details have been changed to protect victims’ identities lForced Marriage Unit, 020 7008 0151 9am-5pm weekdays, 020 7008 1500 out of hours, fmu@fco.gov.uk; www.fco.gov.ukforcedmarriage