Bertie and Sir Roderick Glossop both blacken their faces to look like the band of "n***** minstrels" who are touring in Chuffnell Regis. Jeeves, of course, uses the phrase "negro minstrels," but Bertie and others use the former.
I don't think there was a racist bone in Wodehouse's body, just as there wasn't a political bone in his body, but just think how much cannon fodder that n-word would give to the PC crowd today.
Whoops! I don't think I used "cannon fodder" in the way I intended. Oh well, it's my bedtime and you can figure it out.