A really lovely old penguin crime book. Lots of fun. Written completely in Upper Class speak.
Lots of jokes about the food in France being rubbish, the lower classes being stupid, and the Dutch being untrustworthy.
The plot hinges on a secret code hidden in the Oxford English Dictionary, and relies on us not knowing that the villainess was brought up in Peru.
The ending is terribly tidy - there are two villains. One is unmasked, and goes happily to be hung. The other (the interesting, morally complex one) instantly takes a suicide pill, thus saving messy discussions of moral complexity.
And the empire is saved.