The BBC's Panorama spent a year filming mums with babies and toddlers pleading for money from passers-by on some of London's busiest roads.
They may be a pathetic and familiar sight on Britain's city streets, but, extraordinarily, these poorly clothed children missing out on their childhoods are said to be bringing in up to £100,000 a year for foreign crime gangs.
The money is taken from the children by Romanian gypsy criminals, and funds mansions and luxury vehicles back home.
Amazingly, the masterminds behind it all say Britain encourages the racket by being too generous with the benefits system.
Panorama reporter John Sweeney observed one little girl, "Alice", four, as she begged for cash around London, holding her hand out to strangers. Her minder, who was barely out of her teens, then took the cash from her.
John Sweeney said: "We filmed Alice for months, watching her use a phone box for a toilet and scavenge food from McDonald's.
Visiting Romania to track down the villains behind the infant beggars, John met Petricia Dragusin who told him: "The blame is with the British state, which gives them money. Some have five sets of benefits."
The reporter also confronted Alice's mother, Denisa Mazarache, in Fetesti, Romania, where she claimed to be "sorry" for begging and said she had now stopped and put Alice in a nursery.
Christine Beddoe, UK director of ECPAT (End Child Prostitution, Child Pornography and Trafficking), said forcing the children to work the streets of London is denying them their childhood.
She said: "It means that they are denied an education, they'll have nutrition issues, health issues," she said. "They'll also grow up believing that this is the only way, or the normal way, of earning a living."
Former Metropolitan Police Supt Bernie Gravett led Operation Golf, which targeted the people behind the child beggars. He said: "This is modern day slavery. How does a four-year-old child consent to be exploited? They won't know that it's criminal to beg on the streets of the UK. They are kids."
Have you seen children begging on Britain's streets?
Do you ever give them money?