From BBC News:

Author Anthony Horowitz says he was “warned off” including a black character in his new book because it was “inappropriate” for a white writer.

The creator of the Alex Rider teenage spy novels says an editor told him it could be considered “patronising”.

Horowitz, who has written a new James Bond book, went on: “Taking it to the extreme, all my characters will from now be 62-year-old white Jewish men living in London.”

Source: Spy author Anthony Horowitz ‘warned off’ creating black character – BBC News