"Halcyon" is a song written and performed by Orbital, dedicated to the Hartnolls' mother, who was addicted to the tranquiliser Halcion (Triazolam) for many years. [1] The song features two samples from earlier international hit singles. The first sample is a backmasked vocal sample by Kirsty Hawkshaw from "It's a Fine Day" by Opus III (1992). Ed Barton, the composer of "It's a Fine Day", receives a co-writing credit for the track. The second is a vocal harmonies sample in the song "Leave It"