It's dirty work but somebody has got to do it - except that the practice of people removing human excrement and sewage with their bare hands was made illegal in India 25 years ago.

That doesn't mean people have stopped doing it. It’s called ‘manual scavenging’ and the Indian government estimates that there are about 600,000 ‘manual scavengers’ in the country.

Official estimates say that one worker dies every five days in India doing this type of work – but campaigners have told Newsnight this is the tip of the iceberg as many deaths go unreported.