The theme song for the series, titled "It Won't be Easy", was written and performed by Justin Hayward, the lead vocalist with the Moody Blues. The theme was produced by record producer Tony Visconti who also composed, with Hayward, the incidental music for every episode. Gridneff hoped that the theme would act as a gentle method of enticing casual viewers into the series. Reaction to the music and Hayward's song in particular, has generally been negative. "SFX" magazine, in particular, has been highly critical of the theme tune: in one issue it was placed twenty-ninth in a list article titled "The 50 Worst Things About SF Ever!" while in another it was placed sixth in a list article titled "The 10 Worst Things About UK Telefantasy". Writer and critic Kim Newman has described the theme as the "worst single theme tune of any TV show ever". Chris Boucher has said that he "hated the music. The incidental music wasn't appropriate and it didn't have the style and feeling it should have had".