Catherine Corless is an amateur historian. She has been called the Erin Brockovich of Ireland, after uncovering the story of an unmarked grave of nearly 800 infants at a former institution for unmarried mothers.

Her work prompted the Irish government to open an investigation into mother and baby homes.

For Radio 4's PM programme reporter Becky Milligan has been hearing the story of one home, and the woman who found out the truth.