The idea for the story came from a conversation between Gaiman and Henry about a possible television series.
Henry suggested a story with tribes of homeless people in London. Gaiman was initially reluctant to commit, as he feared that making the homeless appear "cool" might cause more young people to attempt to emulate the characters, but decided that the effect could be avoided by making the story more removed from reality.
(PsychoChomp, Thu 7 Mar 2013, 9:34, Reply)