Can't help feeling Stephen was badly served by this version of him, though I do get outlines of the character the scriptwriter was trying to convey. Someone who feels himself fundamentally powerless, who can't oppose the Gentleman because, well, he has no authority to do so. In his position within Sir Walter's household he has authority, dignity, gravitas; outside it, he knows he's a black man in a white country that has, yes, white fairies, and all he can do is say 'oh please no' and advise Lady Pole to be grateful that their piteous fate is no worse than it is. (Compare and contrast with Childermass, who never struck me as a servant at all. A man of business doesn't merit Lascelles sneers about 'send the servant away.') Much prefer the book Stephen who uses what his position has taught him to exercise what power over the Gentleman he has.
(There's a missing scene I wish they'd kept in that gives us Stephen's background in Sir Walter's house. They were raised together and had the kind of intimacy one gets even when one boy is an aristocrat and the other of the serving classes. "We haven't been able to have any of our old talks lately," Sir Walter says. "I've missed them." If the relationship reminds me strongly of Shidou and Ageha-- minus the unrequited love but plus the utter blockhead imperviousness of the aristocrat-- well, it would.)
And Childermass, ah well, is Childermass. Even in the book I kept getting an odd sense of conflation between him and the Raven King: tall man with long black hair and more of a magician than he ought to be. So he's not: Vinculus knows more of what's going on than he. But Childermass is otherwise never wrong about things, and that kind of character bears watching. Wish she'd get a move on with the sequel...
Do love the northern accents, his and Norrell's. What I know about English accents is minimal, and the one time I was in Yorkshire I could only understand what people were saying by psychic interpretation (much later, this gift allowed me to understand what babies who can't talk are trying to tell me) but the softness and homeliness of it is most appealing.