SunnySusie
I have just watched all of The Reckoning on iPlayer. Absolutely brilliant performance by Coogan. I agree it didnt necessarily add anything to the story, but I thought it was important to remind us all of the dangers and how even the most lauded celeb isnt necessarily OK. I think we need to remember its dramatised and some of it is conjecture. I dont think anyone knows what Savile's mother thought of him. I dont think there is any evidence Savile went to confession and mentioned his 'friend' the sex offender, nor indeed is it clear how he reconciled his faith and his actions, or even if he felt he needed to do this. Its entirely possible he felt no guilt if he was a narcissist, because he would only be capable of seeing his own viewpoint. Not excusing him, but there cant be much doubt he suffered from severe personality disorders.
I think the dramatised scenes are when there is a collection of bits and pieces that are known to the researchers, but are not enough in themselves to tell a story, or that would take the drama in too many different directions, so the scriptwriters include them as a composite character or scene. It's not inventing anything, but presenting things slightly differently. It can also be done to protect the identity of someone who doesn't want to be named.
In the case of Savile's relationship with his mother, it might be that they have spoken to people who knew the family and had been told things she had said, or had witnessed incidents. It would be impossible to show all these conversations, but put together in a scene where the mother combined them they can give a general idea about how it was. As you say, we have to remember it was a drama.