Brigette Sicat will not be going to school today. She sits, knees to chest, in a faded Winnie-the-Pooh T-shirt, on the double mattress that makes up half her home. At night, she curls up here with her grandmother and two cousins, beneath the leaky sheets of corrugated iron that pass for a roof. Today, the monsoon rain is constant and the floor has turned to mud.

Brigette, 10, and her 11-year-old cousin, Arianne, aren’t in school because they have a stomach bug. There is no toilet and no running water, and no means of cooking other than over an open fire. Even when she is well, Brigette is often too hungry to tackle the 10-minute walk to school. Brigette’s mother is a sex worker. And Brigette knows that somewhere, far away, in a barely imaginable but often-thought-of place called England, she has a father. She knows only his given name: Matthew.

Asked what she would say to him, were she able to send him a message, Brigette is at first stumped for words. Then she bursts out in Tagalog: “Who are you? Where are you? Do you ever think about me?” Her grandmother, Juana, her fingers swollen with arthritis and suffering from a lack of medication for her diabetes, sits by her side.

Juana, Arianne, Brigette and Arianne’s brother, Aris, survive on 200 pesos (£3) a day, contributed by Arianne and Aris’s father. (He drives a Jeepney – a public transport vehicle originally converted from Jeeps abandoned by the US military.) Juana, 61, tells me she thinks she may not live much longer. But she wants the girls to finish school, to keep them from working in the bars.

Brigette Sicat, 10 (on left), with her cousin Arianne, 11, and her grandmother Juana. Photograph: Dave Tacon

These are the slums of Angeles City in the Philippines, and the children here represent a United Nations of parentage. Their faces tell that story – fair skin, black skin, Korean features, caucasian. That’s because their fathers, like Brigette’s, are sex tourists.

You can see these slums on Google Earth – a tumble of rusty corrugated iron and rubbish dumps stretching from the streets down to the river. When you visit, it is the smell, like soured milk, that hits you first. Closer to the dump, it is more pungent. Here you will find the poorest of the poor – including the women too old for the sex trade – earning what they can from combing through the fetid piles, looking for plastic and metals they can sell. There is the noise of motorbikes and rain and cocks crowing. The men hold cock fights nearby, the birds fighting to the death. It is illegal, but so is prostitution.

With the 'girlfriend experience', you pay a woman to be your 'girlfriend' for a day, a night, a week or a month

The men who live here are construction workers building the hotels that support the sex tourism industry, or drivers, or security guards. The children run at their heels or in the gutters, or play a game involving throwing flip-flops at an old tin can. The mothers are often themselves the children of sex workers and foreigners without a name; these young children are a third generation abandoned by their fathers.

Melanie (left) and Madeline delos Santos, 18-year-old twins who recently made contact with their English father, Ron. Photograph: Dave Tacon

Angeles City, 85km north-west of Manila, is hardly the only place in Asia with a sex tourism trade, but it is one of its centres. There are perky Facebook groups and dedicated websites that cater to the men who come here: Angeles City, they say, is a place where “you can’t help but get laid”.

The speciality of the town is the “girlfriend experience”, or GFE; you pay a woman to be your “girlfriend” for a day, a night, a week or a month. This can include going on holidays to one of the beautiful resorts out of sight of Filipino poverty, or just staying at a client’s hotel, meeting his every desire.

This is how Brigette’s mother, Aiza, met Matthew, a regular visitor to the city’s sex bars. He visited at least twice a year and often saw Aiza. When, after a few visits during which he had been her “regular”, she told him she was pregnant, he said he had already paid for the sex: it was her fault if she got pregnant.

The red light strip on Fields Avenue in Angeles City. Photograph: Dave Tacon

When Brigette was two, the family heard that Matthew was in the area again and took her to see him at the bar he favoured, but couldn’t get inside. Two years ago, the bar closed down. Since then they have heard nothing of him. Meanwhile, Brigette’s mother has abandoned her daughter to the care of her grandmother.

The Spanish colonialists named this place Pueblo de los Angeles, or “Town of the Angels”. During the Vietnam war, it was the home of the Clark air base, then the largest American military facility outside the US. The base stayed open until 1991, when an eruption at Mount Pinatubo, the volcano looming 10 miles to the west, precipitated its closure. It is now a commercial airport and business centre, with call centres, hotels and restaurants.

According to the local department of tourism, more than 4.7 million foreigners come to the Philippines each year. Of these, 1.2 million are men who arrive on their own. Most numerous are tourists from Korea, the US, China and Australia. The UK is ninth on the list, closely followed by other European countries. In 2011, the then US ambassador to the Philippines, Harry Thomas, said at a conference that 40% of male tourists visited the country for sex alone. Philippine officials complained; he couldn’t back up the statistic, and went on to apologise to the foreign secretary. But nobody who has been to Angeles City doubts that he was right. It is possible, here, to go for weeks without seeing a western woman. It is all Filipino women and foreign men.

On the blogs and social media sites that cater to them, the men who visit Angeles City discuss their experiences and share tips. On one, a man writes: “I never had problems with the women I brought back to the hotel. No ID check. I could bring in as many women as I wanted… not a word was said when I would walk up with two or even three women at a time.” Another man comments on the number of “working girls” who have children by their clients, or “mongers” as the men call themselves – short for “whoremongers”. “I would say 40% to 50% of the working girls in AC had their first kid from a monger, either European, Australian or American, and these mongers aren’t supporting their kids, just left them. I don’t know how you sleep at night.”

The man goes on to wryly acknowledge his own transgressions: “I took an unopened box of 40 condoms with me to AC, I came home with an unopened box of 40 condoms.”

***

It is 22-year-old Judith Icaru’s day off, which means for once she is here, in the tiny two-room house she shares with eight members of her family, including her three-year-old son, Jaden. Jaden’s father is an Englishman in his 50s called Colin. He met Judith in a bar and they had one night together. Judith, then 19, was new to sex work. About 10 weeks later, she realised she was pregnant.

She and her 18-year-old sister, Joy, work in one of Angeles City’s largest bars. They are two of the dozens of dancers who work between 6pm and 3am, hoping to attract a man who will pay to take them away for sex or, even better, the girlfriend experience. Judith gets paid 180 pesos (about £2.70) a night. If a man buys her a drink – known as “lady drinks” – she gets a commission on the sale. “The men like us to drink alcohol. They get angry if you want a soft drink,” she says. She has become adept at pouring drinks on the ground when the men aren’t watching; being drunk would be dangerous.

Judith Icaru and her son, Jaden, three. Photograph: Dave Tacon

The job is made sustainable by the men who pay a “bar fine” – a price set by the bar for taking her away for the night, or longer. A typical bar fine for one night is 3,000 pesos (£45); of which Judith gets just under half. If the client wants her for longer, she might be away for days. The family looks after Jaden.

But today she is here, chatting while her son takes his siesta. The house is tiny, but has a toilet, running water and a television. Her father is a construction worker, building a new hotel. Jaden, meanwhile, does not resemble anyone in her family. He looks like his father, says Judith.

DNA-testing businesses advertise in the bars, on drink mats that promise 'results which leave you with no doubts'

What would she say to Jaden’s father, if she could? She smiles and shrugs. He is far away. He touched her life. He is gone. What does she want for Jaden? “Like all mothers. I want my son to be healthy. I want him to finish school.”

***

When Nely Pones, 45, got pregnant with her daughter, Michelle, nine years ago, she hoped for a long-term relationship with the father. David is Scottish, and told her he was working in Bahrain. “At first, he just bought me a drink. And then the next time he came to the bar, he paid for three weeks for me to be his girlfriend. He paid 31,000 pesos (£460).” David talked of marriage. “He treated me well. He was just an average guy, not too demanding.” But by the time she found out she was pregnant, he had started a relationship with another Filipino woman, whom he later married.

David told Nely he would support the child if she would pay for a DNA test to prove paternity, though he also offered her money for an abortion. Angeles City has a number of DNA-testing businesses. They advertise in the bars, including on drink mats that say: “We understand how important it is for you to have results which leave you with no lingering doubts.” But the cost – 14,800 pesos (£220) – was beyond her reach.

Nely Pones with her daughter, Michelle, nine, whose Scottish father asked for DNA proof of paternity. Photograph: Dave Tacon

Nely never seriously considered an abortion. Michelle – any child – is “a blessing from heaven”, she says. Three years ago, when Michelle turned eight, Nely’s friends told her that David was in Angeles City again. She took Michelle to meet him. “I told my daughter: ‘Give your father a hug,’” she says. Nely cries as she remembers him pushing Michelle away, saying that she was not his daughter.

For years, Michelle and Nely struggled on the edge of starvation. Then, an American stranger, who saw a news report about the lives of women in the area, got in touch through a local fixer and began to support her with a regular payment. It was enough to allow Nely to take out a small loan and buy a fridge. She opened a tiny food shop, built out of waste from building sites, from which she sells rice and fish stew to passersby. She makes about 2,000 pesos (£30) profit a week. On this, she supports Michelle and Michelle’s half-brother.

David would now be in his mid-70s. Using the scraps of documentation Nely has kept, the Guardian tried to track him down. There are a number of people with his name in Britain and Bahrain, none of whom could be contacted. The phone number he gave her is no longer operational.

***

Justin Quintero, 17, would love to connect with his British family. His mother, Shelly, thought she was in a better position than her colleagues at the bars; Justin’s father was her regular. He visited several times a year and would pay to take her away for weeks at a time. Justin’s father told her only his first name – Franz, although she now believes this was a nickname. Shelly was 24; Franz was about 50. He never answered any questions about his home life, but she once saw a photograph of him with his British children on a camping trip. They were all in coats, she remembers, and it looked cold.

'He knew it was his kid, but he didn’t want to be involved.' He met and held his baby son only once

Their relationship lasted five years. She regarded herself as Franz’s second wife and had two children with him – Justin and his 16-year-old sister, Jasmine, who was adopted at two by relatives in Manila because Shelly could not afford to support them both. When she told Franz she was pregnant with Justin, he had mixed feelings, she says. “He knew it was his kid, but he didn’t want to be involved.” He met and held his baby son only once.

Justin Quintero, 17, and his mother, Shelly, 41, who saw Justin’s father for five years. Photograph: Dave Tacon

For a while, Franz sent her 5,000 pesos a month (£74) to support his son. But when Shelly became pregnant with Jasmine, the money stopped. Months later, a stranger from Britain sought her out. He said he was Franz’s best friend, and that Franz was dead. On his deathbed, he had asked his friend to find Shelly and give her money. The friend handed over 20,000 pesos (£300).

Now, at 41, Shelly is too old for the bars. She works as a housemaid for a middle-class family and earns 4,000 pesos (£60) a month, of which she must spend almost half on transport. Fortunately, she does not pay rent; the concrete shack she shares with five family members is owned by her mother.

Justin wants to be an engineer, but knows he will more likely have to leave school soon and find work nearby. He often thinks about his siblings halfway across the world. “I realise it is only a tiny chance that I will ever meet them. I realise they don’t know I exist.” He wonders about their lives; not having a father, he says, feels “like a hole inside of me”. Justin is tall and fair-skinned and recently started shaving. Looking at him next to his mother, who is short and dark-skinned, one can only suspect that somewhere in England there is another family with whom he shares his strong jaw, thick eyebrows and penetrating gaze.

Jasmine and Justin have no proof of their parentage. Even if Franz had been willing to sign their birth certificates, he was not there when they were born. The Home Office states that children born overseas to a British father can become citizens “provided there is satisfactory evidence of paternity”. That means birth certificates, DNA tests or “any other evidence… the home secretary considers to be relevant”. If his siblings were prepared to take a DNA test, Justin could satisfy that test. But he isn’t sure that he wants to – he’d just like to meet his family.

The UK is also party to international agreements that mean child support orders can be enforced by Filipino mothers against fathers in Britain – in theory. In practice, this is a fiction. The mothers would need a court order in Britain or the Philippines; hiring a British lawyer to bring a case would be impossible, and taking action in the Philippines would almost always mean paying a bribe.

***

Today, Ron, a retired civil engineer, is in his late 70s and lives in England. Twenty years ago, he was working in the Philippines. There, he met Esperanza delos Santos – known to her family as Espy – who was 22. She worked in Misty’s bar on Fields Avenue, which has long since closed. “He really wanted me,” Espy remembers. Not only did Ron court her, he also courted her family, meeting Espy’s mother, Myrna. Ron was a good man, the family agreed.

When he was transferred to Indonesia, Espy moved with him. She returned home when she was seven months pregnant and gave birth to twin girls – Madeline and Melanie. The family have a faded picture of the christening, with Ron holding one of the babies.

Madeline delos Santos is determined to be an architect. Photograph: Dave Tacon

The relationship failed, but Ron sent money each month and gave Myrna a letter confirming that the twins were his children, and consenting to their use of his family name. Then, on retirement, he made one last payment – 1.5m pesos (£22,000), with the instruction that it be used to buy a house.

For a while, the girls lived there with their aunt, but today it is used by other family members. The twins, however, were able to attend a private school and gain a decent education, thanks to a Filipino uncle who sent home remittances from his job as a waiter in Dubai.

Myrna asked for more money from Ron in 2011, when the twins were 11, to help pay their school fees. He wrote back, telling them he had no job and no income. “We cannot avoid a difficult decision to make about the twins,” he said. “With both of us without money and still some years to go before they are independent, the only option I can think of is adoption. I hate to say it, but what else can we do?” That was the last they heard from him.

A few years later, the girls’ uncle tracked Ron down on LinkedIn and sent him messages. They say he did not reply. In May last year, Melanie and Madeline turned 18. The family had no money to send them to university, so they looked for work: Melanie is now a shop assistant and Madeline works in a hotel.

Melanie delos Santos: ‘Does he ever think about us and consider us as his children?’ Photograph: Dave Tacon

I meet Melanie at a McDonald’s just off Fields Avenue, before her hour-long journey to the mall where she works. All she wants, she says, is to know her father and have some contact with him. She doesn’t want his money. She understands he has no job. “Does he ever think about us and consider us as his children?” she says. “Why doesn’t he even try to contact us? We are longing to have a father, to see him and know what’s going on with him.”

Madeline, however, is determined to be an architect. After two years’ work, she thinks, she might be able to save enough to put herself through further education. She, too, insists she does not want money from her father. But she does want his attention. “I am hurting right now, hurting and angry. I say to him, I will try to forgive you but please communicate with us and be a father to us… we want you in our lives.”

At the twins’ request, the Guardian located Ron and rang to tell him about his daughters’ request. After a few days and some emails, he called Madeline. They had a good conversation, she says, and agreed to keep in touch.

Meanwhile, in a series of emails, Ron indicated that he did not want to go into details with the Guardian. Asked about the email in which he had suggested the twins be adopted, he said: “After I had supported the twins, purchased a house and provided at least some means of continuous income, I then continued to get further requests for money. I had nothing to give and knew that if I somehow managed a small amount that the requests would continue… Adoption had been mentioned to me as a solution from the Philippines – it was not my original idea.”

Ron gave what he thought was fair, more than many fathers do. But it is much less than he would have had to give, by law, had his daughters been born in Britain.

***

In a packed schoolroom, Brigette sits with her 45 classmates and chants her way through a spelling lesson in English. It is the day after we first met and she is happy to feel well enough to come to school. Her teacher says she is one of the brightest students, but has been held back a year because of non-attendance. The school principal says the children need raincoats and the school needs more classrooms. What would she say to the absent fathers of her pupils, those who have abandoned their children? She smiles. “No judgment. Perhaps people fall in love.” But, she adds, “fathers should support their children”.

Brigette has not yet decided what she wants to do when she grows up. She might like to be a teacher, as long as she could stay with her grandmother, Juana. She has never been to the strip of bars on Fields Avenue, except for the time she was carried there in her aunt’s arms as a two-year-old, in an attempt to meet her father. Juana hopes she will never need to go again.

Some names have been changed for legal reasons.

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