The inquest into codebreaker Gareth Williams' death threw up many still-unanswered questions about the circumstances surrounding how he died. Here, Dr Sian Williams examines more closely some of the evidence that came to light during the eight-day hearing and, given the nature of the young Welshman's work for the security services, asks if we will ever know some of the most crucial detail! Journalist and executive producer Ashley Byrne joins Sian as they work through some of the evidence from the hearing with a series of guests with an interest in the case.

Death of a Codebreaker is presented by Dr Sian Williams with contributions in Episode 3 from from Ashley Byrne and Dyfan Rees