This song is about Ed Sheeran's Irish grandparents, Anne and William Sheeran. (Nancy is a diminutive of Anne, and Bill is short for William.) It tells the story of how they fell in love and married, despite their Catholic-Protestant divide.
William studied and practiced dentistry in in London. It was there that he met a nurse at London's Guy's hospital, Anne Mulligan, and married her in 1951. Sheeran explained to Zane Lowe on his Beats 1 show.
"One was Protestant and from Belfast and one was Catholic from southern Ireland. They got engaged and no one turned up to the wedding. He melted all his gold teeth in his dental surgery and melted them down into a wedding ring. They wore borrowed clothes to get married and had this sort of Romeo and Juliet romance which is like the most romantic thing. I thought I'd write a song about it and make it a jig."
Sheeran previously sang about Bill on the x track "Afire Love". Divide also features the song "Supermarket Flowers," in which Sheeran pays tribute to his late grandmother.
Antrim-based folk group Beoga back Sheeran on this song. They also helped create another Irish-based Divide track "Galway Girl."
Nancy Mulligan is his living paternal grandmother, while the grandmother he sings about on his track "Supermarket Flowers" is his deceased maternal grandmother. Irish news network RTE visited Ms. Mulligan at her Irish home in March 2017 to play the song written for her to her for the first time.