Juliet's publisher and the brother of Juliet's best friend Sophie. Although he shares a professional relationship with Juliet, Sidney is perhaps her closest confidante and friend throughout the novel. The two grew up with one another and are 10 years apart, but only grew into close friends as adults. A majority of the present-day action in The Guernsey Literary and Potato Peel Pie Society is disclosed through letters between Juliet and Sidney.
Extremely level-headed, Sidney largely functions as the voice of reason for the spontaneous and sometimes rash Juliet. He provides an objective opinion for her on everything from her love life to what her next book should be about to whether she is being an utter idiot. Juliet relies on Sidney's suggestions and observations so strongly because he is unwilling to be anything but honest with her. While she needs him on a professional level, Juliet values Sidney's companionship as a loyal friend above all else. Sidney seems like a potential love interest for Juliet throughout much of the novel, but it is later revealed that he is actually a homosexual and the two could never be anything more than close friends.