Imagine eight children, all former slaves, singing their hearts out to the President of India. Imagine this taking place in the grand and opulent Rashtrapati Bhavan Palace, New Delhi, once the seat of the viceroy of India at the time of the British Empire. It's a poignant song: "Give us back our childhood". Their own childhood was stolen from them years ago. Most of them weren't even 10 years old when they were forced to work in unimaginable circumstances, denied the chance to attend school, even to play like other children around the world. Their lives were changed when Indian child rights activist and now Nobel Peace Prize winner Kailash Satyarthi rescued them. Over the last 30 years, Kailash has fought against the economic exploitation of children. He himself has freed over 80,000 minors from brick kilns, garment factories, mines and brothels across India. I was at the Rashtrapati Bhavan Palace when they were singing, this past Sunday. Their song marked the launch of Kailash's new global campaign "100 million for 100 million" which aims to harness the voices of the world's better off children to speak out for their disadvantaged counterparts. As I sat alongside prominent global leaders, Nobel laureates and royalty from across the world including Tibetan spiritual leader the Dalai Lama, former Australian Prime Minister Julia Gillard, and Holland's Princess Laurentien, I was overcome with emotion to be privileged enough to witness such an historic event. For the first time in India, child slavery is officially being recognised by the highest authority. And when Indian President Pranab Mukherjee publicly called for humankind to recognise that children must have both freedom and opportunity, tears welled up in my eyes and a lump formed in my throat. It has been over 200 years since slavery was abolished, but sadly it still exists all over the world. Many of those forced to work without pay and denied their basic human rights are indeed children. According to the International Labour Organization (ILO), there are 168 million child labourers across the world, with more than half involved in hazardous work in sectors such as agriculture, mining, construction, manufacturing and services. The ILO also estimates that 5.5 million of these children are enslaved -- born into servitude, trafficked for sex work, or trapped in debt bondage or forced labour. The number of children in slavery is certainly much higher: 10 to 15 million, according to most specialists. The Nobel has really had an extraordinary effect. Attending this historic ceremony in Delhi on Sunday, I thought that the Committee who awarded the 2014 Nobel Prize to Kailash Satyarthi - jointly with Pakistani schoolgirl Malala Yousafzai- could never have anticipated the impact of their decision. They certainly could have not predicted that two years later the president of the biggest democracy in the world would stand alongside Kailash and the children that he saved from the hands of human trafficking gangs. It's refreshing to see how the Peace Prize motivated Kailash Satyarthi to do even more for the disadvantaged and neglected children in his country, and in the world at large. Instead of seeking worldwide fame, Kailash knocked on the door of the presidential palace and asked the president himself to take action to end child exploitation. Up until now, the Indian authorities have been in denial about the existence of slavery despite 18 million people being enslaved in the country, according to Walk Free. And that's why Sunday's meeting was so symbolic: the head of the nation spoke up in ways that cannot be ignored. The Nobel Committee, the President of India and most of all Kailash Satyarthi should be acknowledged for their courage. What happens now, both in India and around the world, should be watched closely: this could well be the beginning of the end of child slavery. Monique Villa