Mystery of "A Yellow Sleuth"

In 1931 a book appeared in London with the title A Yellow Sleuth: Being the Autobiography of ""Nor Nalla"". It was met with puzzled enthusiasm, TheStraits Times commenting that the book ""presents an interesting problem of distinguishing fact from fiction"". In the words of Philip Holden's introduction, "Nor Nalla" is an ""impossible fantasy of hybridity"".