Part of a wave of singer/songwriters who followed a path carved out by Paul McCartney and the Bee Gees, Gilbert O'Sullivan created his own distinctive pop persona that relied on lush, dulcet melodies and clever lyrics. O'Sullivan's touch was so soft, his arrangement so opulent, that his hooks tended to obscure the dark undercurrents in his songs, especially on such early hits as "Nothing Rhymed" and "Alone Again (Naturally)." After the latter became an international success in 1972, going so far as to top the Billboard charts in America, O'Sullivan's singles and, eventually, a...