Unkind, Geoff, but chacun a son gout.As has already been said, Eva Cassidy didn't fit into any of the conventional "categories", and so was not considered worthwhile in her lifetime by the media moguls.
Nice to see them proved wrong again, sad she didn't survive to enjoy the benefits.
If you can live on in your recorded music, it is an immortality most musicians would choose.
The lesson is simple, produce a record of simplicity and charm and send it to Terry Wogan's producer, Paul Walters c/o BBC London. If he likes it, Wogan will play it, as he does many other folk and country/folk-oriented artists.
As far as I know, being dead is not a required qualification. Ironic that it's often a good career move, though!