40 years ago the Khmer Rouge were toppled from power in Cambodia, having taken over in 1975.

The extremist communists had orchestrated a mass social engineering project forcing millions of people into brutal labour camps and executed professionals and intellectuals.

By the time they were defeated in 1979, around two million people had been killed, about a quarter of the population.

Sokphal Din was a teenager who survived ‘the killing fields’.

Witness History: The stories of our times told by the people who were there.