According to a Facebook post, “Agnes” is Dave Bayley’s favorite song on How to Be a Human Being.

Each song on the album is represented by one of the characters on the cover; from the band’s official “mood board” we learn that Agnes is “a boy, male, 20s, Indian” and “probably lives in a loft apartment”. He is the man holding several cameras, pictured on the centre of the album cover.

“there are varying degrees of autobiography and my own life in each song i write…but for the most part, that stuff is buried and clouded in fiction or blended with other peoples’ lives that i’ve heard about in taxis or at parties or on the street. But there is one song that stands apart from the rest. it is the most truthful, honest, and personal story i have ever written. and that song is ‘Agnes’.
as soon as i started writing it i knew it would be the album closer. the lyrics came out quite quickly and then i spent a while fitting in references to time and life and its natural cycle. weeks, minutes, seconds, birth, breaths, death…etc. I tried to push those themes into the music too…with recurring loops, lullaby melodies, and synths that pull up and down and in all different directions at the same time. it was a tough one to record, and the only way i could get the vocal right was to record it with the vocal mic held close in my hands alone in a small room and finish it just as intimately as it started. i often get asked in interviews “which is your favourite track on the album”….and my reply is always “don’t be ridiculous….i could never choose….that’s like choosing a favourite child.” but i’m not sure that rings true anymore. Agnes is the one. it’s my favourite song on the record, and the saddest song i will ever write. probably. I hope you like it.
Big Love,
Dave”

While Bayley and the rest of the band were initially vague about the song’s subject, an NME article about subsequent album Dreamland made it clear that the song is about a friend of the band who died by suicide.