Marianelli loves animation and especially stop-motion. "I wanted to run away with the circus, and be part of what they were doing," he admits. "The extra appeal, on this movie, came from the space that seemed available to the music: there was a chance to start contributing very early on to the sound of the 'music machine' that Fish and Eggs build together.
"For example; there was a big dance scene in need of music for the animators to work to, and generally there was a huge scope for characterization of the different worlds: the underground cavern, the upper-class cheese loving world, the evil and silly ambition of the red-hats. It was pretty irresistible."
Marianelli, who previously scored the Disney animated short devoted to Victoriana, "Tick Tock Tale," was mostly inspired directly from the movements he saw in the characters, particularly the Boxtrolls themselves. "Their hopping gait, the way they moved around, a cross between a wallaby, a skipping kid and a squirrel, gave me some of the rhythms that accompany them on their night scavenging missions."
The composer also relied on a rich and layered storytelling to provide musical ideas: "An identity crisis to offer lovely ambiguities, which I tried to explore musically, a daft and pompous upper-class, to exploit musically for their pedantry, and a bunch of hopeless baddies, also with their own identity crisis."
Overall, the score offered a chance to have fun with sounds and orchestration: the list of instruments heard at one point or another includes smashed light bulbs, music boxes, toy pianos, dulcimers, rubbed glasses, accordions and barrel organs, a theremin, a bowed saw, mandolins, and, of course, a typewriter.
The montage charting Eggs' growing up is almost completely covered by a phonograph song. In fact, it starts life with a tune on a found music-box: that is the first element of a sprawling music-machine, which the paternal Fish and Eggs (Isaac Hempstead Wright) build and enlarge over the years.
"Because the first element that goes into the music machine is the music box, everything else that comes subsequently, like the phonograph record, had to somehow 'work' musically with the music box tune. It was a gradual process for us to come to what is in the movie now: first we chose a tune for the music box. Then I wrote the basic tune for the phonograph song in a way that it would fit together with the music box tune. I asked the directors to let me write the lyrics of the barber-shop song, and I decided to set to music a list of Italian cheeses.
"For a while I thought that the song would be heard only in fragments, interrupting or merging with the film score each time the scene cuts back to the music-machine and the phonograph spinning. I worked on that idea for a while, but pretty soon we all realized that having one long uninterrupted song, going through the montage, and also spilling over to the next section, with the trolls being rounded up and taken away by Snatcher, would provide the necessary glue to keep this whole part of the story together."
But the centerpiece is the frantic waltz, in which Eggs struggles uncomfortably among the aristocracy yet is irresistibly drawn to the winsome Winnie (Elle Fanning). "I wrote it very early on just piano, so that the animators could start their work on this intricate sequence as soon as possible. It really is an amazing feat of animation, I think: for a while, before I came on board, they had some temp (usual suspect, Tchaikovsky). I proposed to them to try using a trick: have an (invisible) trio of musicians playing at the party, on a slightly out of tune piano, a fiddle and a cello.
"They are already playing when Eggs and Winnie arrive to the house, and continue playing through, starting the waltz. But, here's the conceit: as the waltz gets going, the party music transitions imperceptibly into score: it carries on being a waltz, but it also takes it upon itself to accompany more exactly what we see happening. It swells into a mini-romance for Winnie and Eggs dancing together, then follows the twists and turns of the dance-with-chase between Snatcher [Ben Kingsley] and Eggs, it negotiates the rhythmical accents provided by some hard cuts, or by a loud slap in the face, and finally it gallops up the big staircase for the climactic cheese-rolling end."