"Williams' Blood" is an autobiographical song, written by Jones and music duo Wendy & Lisa, explaining how Jones takes after her mother's, Marjorie Jones née Williams, musical side of the family rather than that of her disciplinarian father Reverend Robert Jones. According to the lyrics, Jones' mother reveals that her grandfather was a musician who traveled with Nat King Cole, womanizing and drinking from town to town. The song describes her family's lament that she isn't more of a Jones like her sister or brother Noel while she expresses her desire to be free. In the song's introduction Jones distorts a line from the first stanza of "Amazing Grace" declaring, "You can't save a wretch like me". At the end of the track when Jones sings the first two lines of "Amazing Grace", her mother Marjorie, a lyric soprano, can be heard singing the same hymn in church. The song's working title was "Keeping up with the Joneses", an idiom heard in the lyrics.
Time Out London described the composition as "among the most personal songs she's ever recorded, celebrating the contradictions between Grace's religious family background and outré public persona". The Independent said the song "employs handclaps and choral refrain to build up an almost gospel fervour".
A music video consisting of clips from the June 2008 Meltdown performance, dubbed with the edited studio version of the song, premiered on Hurricane's official website in early January 2009. It was uploaded onto YouTube on February 5, 2009. A Chris Cunningham-directed music video was reportedly in production in late 2008 but remains unreleased.