In the late 1950s a newspaper ran this small ad: 'Can Catholic people in London or the Home Counties offer a permanent home for an attractive baby girl aged one year who is above average intelligence?’ That girl was Teresa Weiler, who was subsequently adopted and raised in a loving family home. Twenty years later she went to read her adoption file. Alone in a room with those documents and totally unprepared, she discovered a terrible secret about her birth parents that would reverberate through her whole life and lead her to make a profound decision. Yet she told no-one about it for decades. Dr Sian Williams hears her story.