Hi Mark,
It just occurred to me to ask if, as you only mention an IGI reference, you have seen John Callister & Louisa Cain's marriage record in the parish register, as this should give the names of both parties' fathers, and probably other useful information as well. This would seem to be the most useful thing to check and would eliminate a lot of guesswork.
By the way, I couldn't find a John Callister aged 64 in Find my Past's 1911 index - have they mistranscribed him?