SURPRISE! Jessie J was joined by The Wanted's Nathan Sykes to perform 'Calling All Hearts'. This image appears in the gallery:Jessie J Live At The Summertime Ball 2014 10. SURPRISE! Jessie J was joined by The Wanted's Nathan Sykes to perform 'Calling All Hearts'. Picture: PA 11 images See the full gallery: Jessie J Live At The Summertime Ball 2014