British folk rock group Steeleye Span had a hit in 1973 (No. 14, UK singles chart) with an a cappella recording of the song Gaudete. Guitarist Bob Johnson had heard the song when he attended a folk-carol service with his father-in-law in Cambridge, and brought it to the attention of the rest of the band. (Unlike the album version which fades up slowly and fades down slowly, the single was at the same volume for the entire length of the song.) This single is one of only two top 20 British hits to be sung fully in Latin (the other was a recording of "Pie Jesu" from Andrew Lloyd Webber's Requiem performed by Sarah Brightman and Paul Miles-Kingston in 1986). Gaudete is also one of only a handful of a cappella performances to become hit singles. When Gaudete was performed on Top of the Pops, the resident dance troupe walked onto the set in medieval-style robes, holding candles, followed by the members of Steeleye Span.
Gaudete is a sacred Christmas carol, thought to have been composed in the 16th century. It was published in Piae Cantiones, a collection of Finnish/Swedish sacred songs published in 1582 in the North German city of Greifswald. No music is given for the verses, but the standard tune comes from older liturgical books. There is a known entry from around 1420 in the Hussite Jistebnice hymnal. The Latin text is a typical medieval song of praise, which follows the standard pattern for the time – a uniform series of four-line stanzas, each preceded by a two-line refrain (in the early English carol this was known as the burden). Carols could be on any subject, but typically they were about the Virgin Mary, the Saints or Yuletide themes. From: https://en.wikipedia.org/wiki/Gaudete
