Paul McCartney used to be co-leader of a group called the Beatles, who were, according to some assessors, either the biggest thing in the history of rock 'n' roll, or showbiz, or both. That does not, however, explain why Paul McCartney is currently running neckand-neck with Elton John for the title of most popular recording artist in the world, nor why he recently re-signed with Capitol records for what may be the largest multimillion dollar contract in history, or at least until Stevie Wonder finishes his current negotiations with Motown.