From Hymnary. org:
John Francis Wade (1711 – 16 August 1786) was an English hymnist who is credited with writing and composing the hymn “Adeste Fideles” (which was later translated to “O Come All Ye Faithful”).
Born either in England or in Douai, France, Wade fled to France after the Jacobite rising of 1745 was crushed. As a Catholic layman, he lived with exiled English Catholics in France for the rest of his life. There, he taught music and worked on church music for private use.
Professor Bennett Zon, Head of the Department of Music at Durham University, has noted that Wade’s Roman Catholic liturgical books were often decorated with Jacobite floral imagery, and argued that the texts had coded Jacobite meanings. Zon describes the hymn “Adeste Fideles” as a birth ode to Bonnie Prince Charlie replete with secret references decipherable by the “faithful”: the followers of the Pretender, James Francis Edward Stuart.