"Bureaucrat", "Civil Servant", "Faceless Bureaucrat"

Back to the Google Ngram again.  The term::

• "civil servant" starts occurring in 1800, in British  English, peaking in the early 1940's then declining.  It starts occurring in the 1880's in American English peaking in the mid 1960's, then declining. It's about 5 times more common in British than American.
• "bureaucrat" starts earlier in British English (around 1840) than in American (late 1860's).  In American the peak is mid 1970's, then a decline.  In British the peak is the early 1990's, then a decline. Usage slightly more common in the U.S. 
• "faceless bureaucrat" is 10 times more common in American English than British, though the pattern over time is roughly the same.

I've had Google alerts for "faceless bureaucrat" and "civil servant" for a few years.  The pattern is for the members of the former British Empire to use "civil servant" quite a bit, and their usage of "bureaucrat" is generally neutral, not pejorative.  The U.S. doesn't use "civil servant" much, and usage of "bureaucrat" usually has an edge.  So the comparisons made available by the Google tool don't surprise me, but I am puzzled by the variations over the last 50 years.