Luna

The song features guest vocalist Rae Morris synchronizing with frontman Jack Steadman. Blackpool singer and pianist Rae Morris filled in for three tracks on So Long, See You Tomorrow, while the band's regular collaborator, Lucy Rose, was on tour. "It would have been great to have Lucy full-time, but it's just not possible, she's a star in her own right," Steadman told NME. "Rae came to one of our gigs and knew Lucy; she sang for us one day when Lucy wasn't available and it sounded great so we kept it."

The accompanying music video, directed by Anna Ginsburg, stars London-based synchronized swimming troupe Aquabatix. "The synchronized swimming aspect of it kind of related to everything that we were doing visually," Steadman said. "It was all about animation and loops, and I thought, when I was picturing these synchronized swimmers, it tied into that quite well." Ginsburg also directed the video for "How Can You Swallow So Much Sleep," from the band's previous album, A Different Kind of Fix.

Jack Steadman explained the birth of this song to NME: "'Luna' began in India. I think that's where I started writing it, but it was very much just a rhythm part and a bass line, and it had a cool sort of essence to it, but it wasn't a song. So I worked on it a bit more. It was kind of a very electronic song at that point; it had kind of a dance hall beat to it. And I was singing a melody in my head, and it wasn't sounding right coming out of my voice, and I'd just been introduced recently to Rae Morris, so I called her up, and I thought maybe this was something she could sing on. And she came around to the studio, and it just worked. It was fantastic ... that was the moment I think where it really became something. Rae and I were so excited about it when we first finished it. We went out that night, and I had it on my iPod, and everywhere we went, we would just want to leave so we could go outside and listen to it again. I think the lyrics kind of come from that night, really, of writing it and going out all night and just listening to it and that kind of twilight moment. And then there's obviously the comparisons between the subject - the girl - and the face of the moon."