The character of Clamb the law clerk was created for the miniseries. He primarily appears in scenes where, in the novel, Tulkinghorn was sitting alone and thinking about information which set up forthcoming plot elements. Making Tulkinghorn able to talk to Clamb eliminates the need for soliloquies, which would not be believable in this narrative format.
I blame my self.
Boythorn: You blame yourself for an act of kindness. No sir, the person to blame is the one who calls himself God. What deity is it that would inflict such an illness on an innocent girl?