What is it about 16-year-old Hayley Westrena? Her 13-song medley of ballads sold more than 290,000 copies in Britain in seven weeks, installing ‘Pure’ at the top of Britain’s classical music charts. (The album will be released in the United States on April 9.) Now, with Ms. Westenra signed up for a $4.5 million five-album contract, Decca may well be tingling with the feeling that salvation is nigh.”