Jackie Kay’s use of Trumpet as the novel’s title and Joss’s instrument of choice contains several implications. As an instrument, the trumpet is symbolically masculine. For Joss, the trumpet allowed him to assert himself as male, forging a path to the jazz world.

Trumpets have long been used to alert people to important announcements—implying that Joss is a herald. Joss is a prophet of coming changes—of women and non-cisgender individuals gaining equal prominence among jazz musicians. Kay frames Joss’s trumpet-playing as being able to bend to the needs of listeners, and even being able to transcend time (thus reinforcing Joss as a herald). In this, Kay proclaims that jazz has the power to empathize, express the deepest human emotions, and break barriers between human beings.

Kay describes the sleeping dreams of almost all of the main characters. Millie dreams of cross-dressing with Joss just before he plays; Colman dreams of saving a deaf child from water rising in a flooded basement; and Big Red McCall, Joss’s bandmate, dreams he is chasing Joss, who carries on a conversation while he fades into the distance. Even the deceased Joss has dreams in which he sees those whom he has left behind.

Kay uses dreams to express the anxiety and hopes of the characters; Colman realizes he must rescue his father’s memory and reputation, and McCall struggles with the notion that he must lead the band.