In Susanna Clarke’s universe of Jonathan Strange and Mr. Norrell, “magic” is a past time for wealthy gentlemen, a genteel academic and historical field of study. The chief proponent of this discrimination between “proper” and “improper” magic is Mr. Norrell. A proper magician, according to him, has no dealings with the wild and pagan beginnings of magic in England three hundred years ago, with John Uskglass, the mortal raised in a fairy kingdom which he grew to rule. A proper magician performs such magic as can be controlled, studied, understood.
And under no circumstances is a proper magician called upon to form any alliances with the fairy realm, ruled by avaricious and amoral creatures whose idea of logic bears no resemblance to that of humans’. Col Tom Blue, for instance, is mentioned several times in this universe as a fairy of great power in the employ of Ralph Stokesey.
If I were a better student of literature I’d understand the implications of colonialism in Clarke’s work, but it’s not so very great a leap to see a possible parallel here: fairies — unearthly, inhuman, yet powerful in their own rights — are able to summoned at any time by a human magician, who can then use fairy powers for their own means. Norell will have no relations with a set of people whose moral code is so different; Strange wants to be able to understand their ways of dealing with the universe and to borrow their abilities.
There’s another interesting implication in Norrell’s hatred of Uskglass and the Raven King mythology. In fact, it’s not even an implication by the time Norrell confesses his true feelings to Strange. Norrell is actually lamenting the fact that Uskglass simply rode out of England and into a fairy realm, abandoning both the country and the practice of magic in the process. Norrell, in his enthusiasm for the field, has had to struggle for decades to teach himself the understanding of magic. He has had no one to turn to, and no tradition to refer to except stories and superstition.
Now, one more logical leap.
John Uskglass seems to have entered a fairy kingdom as a young child, and treated as a slave by the rulers of the time. Eventually — either by being taught magic or having an extraordinary facility for it — he rose to rule both fairy and human (that is, the United Kingdom) realms. It is not so hard to see the parallel between him and Stephen Black, a man who has assimilated so well into high English society that his natural urge upon seeing the gentleman with the thistledown hair is to serve him as well.
All this, of course, is by way of saying that the BBC adaptation of Jonathan Strange and Mr. Norrell is fantastic, both in execution and in faithfulness to the original.