Like Westmark, The Kestrel owes a significant debt to the people and events of the Enlightenment era, as well as Lloyd Alexander's experiences in the Second World War.

When discussing The Kestrel, Lloyd Alexander specifically cited Goya's Los Desastres de la Guerra as a stylistic and thematic influence.

"[2] Like his Chronicles of Prydain, Alexander acknowledged that "an awful lot of situations in Westmark" were inspired by his service in World War II.

[3] When addressing a 1985 conference of the Children's Literature Association, he specifically noted that "in The Kestrel and The Beggar Queen I relied upon my own experiences and observations of some forty years ago.

Theo insists upon joining the students and the leaderless troops to conduct irregular operations on the supply lines of the Regian military.

In response to political turmoil, her chief minister begins to restrict press freedoms and crack down on public defeatism.

Recognizing that the political situation has become extremely tricky, and tiring of the war, Mickle and Las Bombas don disguises and infiltrate Regian headquarters.

Amid all of the upheaval, Theo and Mickle agree to postpone their marriage so that he can participate in the legislature while she reigns as Queen of Westmark.

"[6] In the School Library Journal, Hazel Rochman compared The Kestrel to Westmark, writing that the sequel had "a more realistic and complex narrative form."

"[9] Writing for the New York Times Book Review, Georgess McHargue complained that "the hand of the puppeteer is too much in evidence here," while conceding that The Kestrel and Westmark filled a need in the market for "political novels for young people.