Used to be Charlotte Church, until she ruined her voice and talent with too much smoking and drinking, and an awful turn toward dance/electro-pop music.
Yes, she was classically trained at a young age and sang various arias and aspired to be an operatic singer but she never truly delve into it.
Her career certainly got waylaid resultant from too little discipline (self and governorship) combined with becoming a multi-millionaire overnight. She could have been a Rene FLEMING had she stuck with it.