Mark Williams-Thomas is a criminologist and former police officer who is now an investigative journalist. If his name sounds familiar, it’s because he was instrumental in exposing Jimmy Savile as a paedophile: you may well have seen the documentary ‘The Other Side of Jimmy Savile’, which he presented.

Now a reporter for ‘Channel 4 News’ and ‘This Morning’ (for whom he covered the Oscar Pistorius trial: more on which later), most of his work comes from ITV; he hasn’t worked much for the BBC since the Savile documentary was aired.

His is a job which must be distressing, as well as frustrating – so why do it? “To help people”, William-Thomas told an agog Funzing audience. “I have a platform to millions of people and getting victims’ voices heard is so important”. That said, he admits he’s unable to help everyone who approaches him.

Having left the police force over despair at its bureaucracy, William-Thomas self-funds the cases he works on, which “makes me happy and satisfied – but not rich”. As you can imagine, there were three cases in particular we wanted to hear about, so we may as well start with the most infamous – and the most baffling.

Williams-Thomas doesn’t bother mincing his words. Jimmy Savile was “a cruel and horrible man, who thought he could do anything – and get away with it”. Which he did: continually. At the point of his involvement, Williams-Thomas knew that Savile had been interviewed by the police, but did not know the extent of the allegations (bear in mind that Savile was still alive). BBC Newsnight wanted to run a programme debating whether the police had failed in their investigations.

Williams-Thomas disagreed with this angle, believing that the right story was Jimmy Savile as a potential sex offender. On this basis, he met with ITV – but they were equally unwilling to touch the story. Yet, “it became clear very quickly that there was something here”.

At Broadmoor, Williams-Thomas interviewed a young girl who described her experience of Jimmy Savile: she would be in the bath and Savile would walk into the room and watch her. He’d been granted full access to Broadmoor, despite having no experience or understanding of mental health issues. Savile was given his own keys to the building, for God’s sake (I’m shaking as I type this, I’m so angry). The 1980s were not that long ago and I find it unbelievable that this TV presenter / “national treasure” could have been granted such privileges).

Jimmy Savile was “a really, really nasty piece of work”. And yet, few people spoke out against him and even fewer were in a position to stop him. Williams-Thomas vividly remembers a former Childline patron telling him “It wasn’t my place to stop Savile” and the investigator believes it would have been impossible to expose Savile when he was alive.

I doubt Oscar Pistorius would thank me for segueing into his section of the talk from Jimmy Savile, but his was the second most high-profile case discussed tonight. And, I suspect, few people have sympathy with him. Whether or not you believe his version of events, the fact remains that he killed his girlfriend, Reeva Steenkamp, in a horrific manner. It was a “mighty fall from grace”, reflected Williams-Thomas; at that time, Pistorius was one of the three most idolised personalities in South Africa, alongside Nelson Mandela and Desmond Tutu. Whilst Pistorius declined an interview with Oprah Winfrey and all other requests for interview pre-trial, he eventually agreed to talk to Mark, who was covering the trial verdict for ‘This Morning’.

Wiliams-Thomas got to know Pistorius “quite well” and told a disbelieving audience that he does not believe the Paralympian intended to kill Reeva. The gun culture in South Africa is difficult for us to comprehend, he explained, and it is feasible that Pistorius thought he was chasing an intruder. Furthermore, he was moved by Pistorius’s response when asked how he felt about the possibility of going to prison for a long time:  he cried, then told Williams-Thomas “I don’t care, because I’ve killed the only person I ever loved”.

From one opinion-dividing event to another: the disappearance of Madeleine McCann. Williams-Thomas travelled to Portugal 48 hours after she went missing and was shocked to learn that the Portuguese police had not requested any video evidence from the holiday resort. As with Pistorius, Williams-Thomas got to know Gerry and Kate McCann well – and doesn’t believe they had anything to do with their daughter going missing. He does, however, think they were mistaken in not admitting at the outset that they should have kept their children in their line of sight at all times.

It remains such a baffling case. The doors to the apartment were locked, although the patio doors were open and the front window was slightly ajar, which would have allowed the intruders access. There’s also some discrepancy over whether, when Gerry checked on the children, he went into the apartment or listened from the front door: accounts vary slightly. But who would ever have thought that a child could be spirited away in that fashion?

What did I learn from this undeniably fascinating talk? Possibly not all that much that was new: instead, it reinforced my view that the truth is complicated and the good guys don’t always win. Certainly, our fascination with crime and punishment remains undimmed. As for Mark Williams-Thomas (a compelling speaker), he regularly receives death threats and his home has been firebombed. “If someone wants to take me out, they will take me out. But most of the people who dislike me hide behind a screen”.