Hi Carol,
Information for John Cain on the LDS website - New Zealand Immmigration Pasenger List 1855 - 1973. There's a total of 998 Cain's listed, not all from the IOM

Regards
Frank

Name: John Cain
Event: Immigration
Arrival Date: 23 Dec 1913
Event Place: New Zealand
Gender: Male
Age: 27
Marital Status: Single
Origin: England
Occupation: Farmer
Estimated Birth Year:
Shipping Company:
Ship: Tainui
Ship's Departure Port: London
Departure Port: London
Departure Date:
Ship's Arrival Port: Wellington
Arrival Port: Wellington (other ports also listed)
Digital Folder Number: 004415987
Image Number: 00464