You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: ALL ABOUT AUTHORS 
Clue: "The Remains of the Day" author Kazuo Ishiguro was a grouse beater for this grandmother of Prince Charles
the queen mother

Category: THE 1930s 
Clue: He was appointed conductor of the Boston Pops in 1930
arthur fiedler

Category: HOLIDAYS & OBSERVANCES 
Clue: This country celebrates Queen Margrethe's birthday on April 16

denmark