This usage is not completely unknown today, but is rare.
But still common when used in reference to prime ministers of non-Commonwealth countries.
Regarding stunt, the OED, which has citations going back to 1878, says:
Originally belonging to the slang of American college athletics; not in the Cent. Dict. 1891 or in Webster 1897; our earliest quots. show that it seems to have been still current only among schoolchildren and college students. Its general colloquial currency, and its extension of application, seems to have begun early in the 20th cent. In British use it was at first regarded as mainly a soldiers’ word.
The 1878 cite is from Samuel Butler, so the earliest citation of an American word is by an English writer. Although the entry does need updating.
Conan Doyle and the women’s suffrage movement seems to be a complex case. Evidently he championed a lot of women’s rights, but opposed them getting the vote. Here’s what his daughter Jean, who rose to become Commandant of the Women’s Royal Air Force, had to say about it in 1990:
Well, this is rather a tricky one! He undoubtedly thought that women were the superior sex—I was certainly brought up to think that I was not inferior in any way to my brothers, that women are more refined than men. He would not have opposed the suffragette movement on the score of women being unsuitable to have the vote, but he was an idealist in many ways—very concerned with the Divorce Law reform, and he had heard of so many cases of brutality in the home, that he did feel that to have a political divergence of opinion between husband and wife would add to all this violence. He also felt, and this is where the idealistic side of my father came into it, that women would probably, in a happy marriage, influence the husband and that in a way his vote would be her vote. But his objection to the suffragettes was that he was so shocked by their violence. He felt that violence was a demeaning feature of human beings and that, while men were brutish in a way, women were above such things, and he was very very horrified that women should have stooped to violent action.
So, in short, he seems to have been as condescending toward women as one would expect any Edwardian gentlemen to be. Perhaps putting the Germans behind the movement is Doyle’s way to explain away how women in the movement could do some of the more extreme acts. (They were dupes of the Germans, of course. Otherwise, no woman would ever act that way.)