First, let's clear up the confusion about Mary's discovery. She appeared on British TV singing Turn turn turn. Among the viewers was Twiggy, who let Paul McCartney know that she might be a bit special. Paul eventually signed her to Apple records. However, even if he hadn't signed her, Mary would probably have got a record deal anyway because of the TV exposure.
The CD itself contains all Mary's hits, both British and American, but the one song which stands out is Those were the days, which was number one in Britain and number two in America. Mary's first love was folk music and that is the basis of her music, although there are pop influences. These had faded by the end of her short career with Apple. The Earth songs album, represented here by the last three songs, was all folk music.
Think about your children is an interesting song which ought to make parents everywhere do just that. Jefferson is a country-flavored song with some banjo. Knock knock who's there was Mary's entry in the Eurovision song contest - it didn't win but I think it came second.
This is a fascinating collection of music by a singer who's career was all too brief.