Thanks Frances. No, I hadn't spotted that. Can I ask was there anything else that pointed you to this birth apart from the illegitimacy? There was one legitimate John Callister in that year that I could see on FamilySearch, but that was in Braddan, and it's a bit daunting to embark on tracing him forward to eliminate him, especially when he's in a 'foreign' parish.

Then there's identifying Elinor Kinley, who she was and what happened to her.

I'm not having much luck with John's wife, Eleanor Cannell either. I see that I'd noted these two as possibles:

Elinor Cannel d/o Robt Cannel & Elr Hingley c. 24 January 1776 Malew

Eleanor Cannel d/o Charles Cannel & Anne Bridson c. 20 Aug 1775 Kirk Rushen

I have this will reference for John Collister/Callister, but I don't think anyone's transcribed it so far. Not sure if it would help anyway!
CALLISTER, John 1821 San E 1 0106422: