Classical covers of pop songs?

Michael Nyman's first string quartet makes use of "Unchained Melody".

https://open.spotify.com/track/31QtP3En7dP18W7jE8ynlJ?si=a02fa5d626fa42b6

The String Quartet No. 1 (1985) was commissioned by the Arditti Quartet. Nyman had attended a performance of Ludwig van Beethoven's Grosse Fuge by the group, and found it the most theatrical performance on a string quartet he had ever witnessed, performed as though Beethoven had been trying to break through the limitations of the string quartet to create an orchestral sound. The quartet was originally intended to be a "compendium" of string quartet literature, but he decided that two pieces from different eras were enough of a contrast. It is built out of three distinct and diverse pre-existing music sources: John Bull's Walsingham Variations, Arnold Schoenberg's String Quartet No. 2, and Alex North's "Unchained Melody". The use of Bull is an homage to his professor, Thurston Dart, who presented Nyman with the Musica Britannica edition of Bull's keyboard works as a graduation gift. "Walsingham" was a popular song in Bull's time, and Nyman's use of "Unchained Melody" (originally written for a 1955 prison film titled Unchained and famously covered by The Righteous Brothers, and the favorite song of Nyman's wife, Aet) is a contemporary equivalent. As noted by Pwyll Ap Siôn,[3] "Unchained Melody" is musically related to "Walsingham", as its opening three-note pattern of C-D-E is a slight variation of the melody of "Walsingham". "Unchained Melody" enters in figure H (measure 274) over a bass line of variation 9 of "Walsingham" that previously appeared in figure E.

https://www.youtube.com/watch?v=I13uVL681oo