She had a hit with Those Were the Days, her debut single, which was produced by McCartney. It reached number one on the UK charts and number two in the U.S. (Cynthia Lennon recorded a version of the song years later which, needless to say, is not quite as noteworthy as Hopkin's version.) Another single, Goodbye, was written by McCartney for her.
It's a little surprising that Hopkin didn't seem to get as famous in the States as she should have been, but when she got married in the early 70s, she dropped out of the music business for a few years. She did return to recording and has been involved in numerous musical projects up until the present. I can't do her career justice here - just to say a couple of her hits are the Forgotten Friday Favorites this week. Enjoy!