Pia Sinha worked in prisons for 24 years before being appointed CEO of the charity Prison Reform Trust and she describes herself as a "ridiculously optimistic" person, who believes the prisons can be made to work properly.

Sinha started her career in prison as a psychologist and went on to work in female, male prisons and institutions for young offenders. She was the governor at three prisons and later was responsible for all the women’s prisons in the country.

Sinha, who believes many of the prisoners in the UK should not be behind bars, speaks to Krishnan Guru-Murthy in the latest episode of Ways to Change the World.

Produced by Silvia Maresca, Ka Yee Mak and Tom Gordon-Martin.