Burt Bacharach and Elvis Costello at the Royal Festival Hall

The stage is in darkness and from somewhere in the wings Elvis sings the opening verse of 'Baby It's You'. It is one of the many treasures in Uncle Burt's bountiful trove of pop classics and Costello's awed, yearning delivery turns Hal David's words into a short sweet valentine. From the dutiful artisan to the exalted artist, sealed with a wish.