Martin Quibell (co-host P2 Podcast Blues) joins the show this week for a look at the 1974 "Dark Horse" tour from 1974.    After an exhausting month finishing some records and rehearsing the band, George Harrison's voice was in no condition for two months of regular shows (sometimes twice daily) across the United States.  The frustrations mounted, but it wasn't all bad.     The band was invited to visit the White House (with Harry Harrison alongside), and the ache of Pattie would be replaced by newfound love Olivia Arias.