The Telegraph today features an article on the song Wild Horses covered by Susan Boyle, and confirms it is as a classic. Written by Jagger/Richards, but recorded by many other notable singers since their own version of it was released, it is reported to concern the relationship between Jagger and Sixties singer Marianne Faithfull.
Faithfull is or was a noted singer in her own right, my favourite track being The Ballad of Lucy Jordan. Worth listening to, whichever side of 37 you are on!