The original 1968 LP issue of McGough and McGear reprinted a handwritten list of “People on a Train.” These famous people included Jimi Hendrix, Spencer Davis, Gary Leeds of the Walker Brothers, Dave Mason, John Mayall, Graham Nash, Paul Samwell-Smith, Jane Asher and a certain Paul McCartney.   The train, in fact, was the studio where Roger McGough and Mike McGear – real name, Mike McCartney – recorded their only album as a duo.  The unconventional yet accessible art-rock classic, produced in part by the future Sir Paul and featuring all of those…