By Damian Grammaticas
BBC News, Kanchipuram, southern India
Seated at old wooden weaving looms, workers are toiling away. The conditions in their huts are like something from mediaeval times. It is dark, dingy, everything operated by hand.
Some of those weaving this fine, expensive cloth are slaves
Stretched across the looms are lines of threads, bright pinks, reds, greens. The weavers are busy making beautiful, intricate silk saris.
But some of those weaving the fine, expensive cloth are modern-day slaves.
Ashok Kumar is one. He is a small, slim boy of 13, busy making delicate patterns in real gold thread along the borders of the sari.
Ashok says he has been weaving since he was nine. He sits working for 12 hours every day, seven days a week. He gets just one day off each month.
He is a bonded labourer, what is also known as a debt slave.
When Ashok's mother died, his father left home. The boy was abandoned with his grandmother. Desperate for money she took £12 ($25) from a loom owner and, in return, sold the boy's freedom.
Ashok is now bonded, forced to do this one job. He is not free to leave unless the debt is repaid. And he is paid just 15p (30 US cents) a day, so there is little hope he will ever do that.
Traded like a commodity
Ashok's boss, Muthu Pereumal, can sell the boy to another employer, trade him like a commodity.
"He will stay here until he is 20 or 22," the boss tells me, standing by Ashok's loom, "or until someone else comes to buy him from me. He will never do anything else but this."
Bonded labour has been illegal in India since 1976. But the laws are widely flouted.
"Because the families are so poor they will give me a child who will work for as long as I want," Muthu Pereumal says.
"In return, we give them an advance of up to £60 ($100). Adults cannot afford to work for such low pay. Without children working like this it would not be possible for our industry to survive."
Kanchipuram, Ashok's hometown in southern India, is built on the silk industry. Sixty thousand people work making the town's famous saris. The local labour union estimates 12,000, one in five, are bonded labourers.
They are also used in many other industries from leather-making to road-building, agricultural labour to silver work. Campaigners say there could be from 10-40m bonded labourers in India.
The government disputes that. In 2004-5 it identified and freed just 866 bonded labourers in the entire country, and claims there are few instances left.
"If any cases of this evil come to light, even a single episode of it, we are committed to eradicating it," says Sudha Pillai, labour secretary in India's government.
"The minute a case comes to light, the minute it is reported, it is investigated. And instances are coming down."
In another courtyard in Kanchipuram, men stripped to the waist are plunging handfuls of raw, yellowish silk into vats of boiling liquid, dyeing the threads pink and green. It is hot, the air thick with vapour. Beads of sweat run down the men's faces. All are bonded.
Dyes are handled without protective clothing in Kanchipuram
Away from his boss, Ashok is willing to talk about the awful conditions he endures.
"Because I work at the loom my hands hurt. Sitting for a long time gives me pains in my back," he says.
"Sometimes I get headaches and my eyes hurt. But I have to keep going until eight in the evening. Only after that can I go home and sleep."
His grandmother says she had no option but to sell the boy into debt slavery:
"He is working like a slave, but what can I do? Whether it is good or bad I don't know.
"Everyone who lives around here does the same. It doesn't matter whether you have a boy or a girl, we send the children to work. We have no other choice."
Far from Kanchipuram, traffic rumbles along Tooting High Street in south London. Britain abolished the slave trade 200 years ago, but products from industries that use slave labour are still sold here.
In his shop, Raj Siva is unpacking Kanchipuram saris. South Indians prize the intricate handmade silks as wedding dresses. They fetch up to £900 each in the UK.
"Whether there are bonded labourers used we don't know," Raj admits.
"It's very hard to track down, India is a very big place, it could happen - we just don't know. We fly out to India twice a year, tell them what we want, and they send it to us."
Raj believes it should be up to India's government to eradicate debt slavery:
"The best thing is it has to come from the top, it has to come from the government, they have to set standards, rules, we are just outsiders we don't know how their practice works."
One boy freed
In Kanchipuram, we met the local Collector. He is the government administrator who runs the district, and who is obliged, by Indian law, to find and free bonded labourers.
The Collector said he knew of no bonded labour cases
"We have not come across any such case of bonded labour, it's a family industry," he told me.
When I told him about Ashok's loom 500m away, he stuttered disbelievingly: "Oh no, I just don't, I just can't... we will have a check, we will definitely inquire into it."
So we took two of his labour enforcement officers to investigate Ashok's case. They had to be cajoled to do their job. First the officers sat refusing to leave their office. Then, as we approached Ashok's workplace, they dragged their feet.
Ashok had left his loom for five minutes. The labour officers could not be bothered to wait. They jumped in their car, and sped back to their office.
Many of the activists who campaign against bonded labour complain that indifference and apathy are the way many Indian bureaucrats respond when confronted by slavery.
Five minutes later Ashok turned up. So we took the boy to meet the Collector. Ashok explained his story, and the Collector ordered the boy be released from his bondage.
Ashok Kumar has gone back to school
Ashok's debts have now been cancelled, he has just started school again, his childhood restored. But he is still waiting for the £250 ($500) compensation he is entitled to under Indian law.
While Ashok is free, thousands more still toil at Kanchipuram's looms, and probably millions bonded in other industries in India, modern-day slaves, in the 21st Century.