Earlier days some of the trains were : Shoranur-Cochin passenger, CHTS-Madras ( currently Chennai-Allp), Howrah-Cochin ( later on became HWH-TVC & now running as SHM-TVC). There were few others as well like Patna-Cochin (Patna-ERS currently). Some other trains were also there....maybe you may have to refer some old archives