“This time, I’m combining three roles - investigator, reporter and presenter. That means I’m able to explain and unpick threads of evidence as they unfold for viewers, interview protagonists face-to-face, and make the narrative of the story clear.", said Mark Williams-Thomas. My profile since the Jimmy Savile programme has meant I am approached by people from all over the world to help investigate cases. Some have been unsolved, some have resulted in conviction, and they involve a variety of things - missing people, sexual offences, possible miscarriages of justice, even murders. Yet the reason for every contact is the same - those people want to find out the truth."

• Mark Williams Thomas