V. No Chinaman must figure in the story. To understand why, one should refer to the following section of the Detection Club’s Oath: “Do you promise to observe a seemly moderation in the use of Gangs, Conspiracies, Death-Rays, Ghosts, Hypnotism, Trap-Doors, Chinamen, Super-Criminals and Lunatics; and utterly and for ever to forswear Mysterious Poisons unknown to Science?”

— Father Knox’s Ten Commandments of Detective Fiction

记得小时候第一次读到Knox十诫，不明白为什么侦探小说里面不能有“中国人”。那时候还不晓得Chinaman是有贬义的称呼，就好像nigger之于黑人。后来逐渐知道Chinaman是指具有特异功能、神秘力量的“东方人”，不一定非得是中国人。Knox提出这一条，主要是针对Sax Rhomer的Dr. Fu Manchu。

Christianna Brand在Fog of Doubt的序言里再次提到Chinaman，给了明确的解释：

One of these was: “there shall be no Chinamen.” By this was meant that scenes and characters should be “real”; the Mysterious East, unknown poisons, anything that was not possible, credible, acceptable to the standards of every day life—all that was out.

另外强烈推荐这篇序言，里面有很多Brand写小说的心得。