Damon Albarn originally intended to release Hong Kong as a solo song under his own name, but it was released as a Gorillaz song without his knowledge. However, Albarn has since stated that he believes that in the end it was the better decision. This is why Damon came out of the shadows during Demon Days Live shows because the song isn't actually a Gorillaz song and was intended for release under Albarn's name.
Original 'Help!: A Day in the Life' Version
The original version of the song (also known as the 'War Child' version) was recorded for the 2005 compilation album Help! A Day In The Life. In this version of the song, the violin accompaniment is completely absent. In fact, until the inclusion of the song in both the Demon Days live tour and the reworked version featured in the D-Sides album, there was little to no knowledge of the track's existence due to the lack of promotion for the song's release by the band.