The material explained below is based on the original Derbyshire theme. Subsequent versions of the theme will be covered in the future, and the ways in which they differ will be covered in their individual sections.
Melody 1 is a hollow, gliding melody, comprised of six notes: a low B, with a portamento ascending two octaves to the C above, and then resting on the high B a semitone below. This is followed by a high D, with a portamento descending back down two octaves to a low A, followed by a low B. Note that the high B from the end of the first part of Melody 1 (Melody 1a) continues for the duration of the second part (Melody 1b).
Melody 1a is defined as the first three notes of Melody 1 (B, C'', B''), and Melody 1b is defined as the last three notes (D'', A, B).
Melody 2 starts with a descending melodic figure starting on a high B, then a G and a B an octave below, implying (together with the E being played in the bassline) an E-minor chord. This is followed by another B, a D, C, and another B. Then, an octave below that, there follows a low A, a low B, a low C, a low D, a low B, and finally a C an octave above, followed by a B, which continues for a few beats.
Melody 2a is defined as the first seven notes of Melody 2 (B'', G'', B', B', D', C', B'), and Melody 2b is defined as the final eight notes (B', A, B, C, D, B, C', B').
The Bridge (sometimes known as the "Middle-8") provides a melodic and harmonic counterpoint to the main theme, with a key change to the relative major key (G). The melody of the Bridge section can be divided into two sub-sections. The first section starts similarly to the beginning of Melody 1, except with a higher A instead of a low B. Then follows (like in Melody 1) a C and a B, followed by a G, a B, an A, and a G, an F#, and a G. The inclusion of the F# is interesting, as earlier in the theme, the bassline uses an F natural.
The second sub-section of the Bridge starts with a low G, followed by a D two octaves higher, then a high E, a high D, a high C, a high D, and a high G. These six notes are then repeated (except the second time, the high G is two octaves lower), and followed by a concluding figure consisting of a high B, a high A, a G, an F#, and a G, which continues for almost 4 bars.