I've finally tracked down some PROOF that John James & Louisa lived at Close-y-garey:

No: 322
When Baptised: 11 Oct 1872
Child's Christian Name: Eliza Ann
Parent's Name: Father: John Callister - Mother: Louisa Cain
Abode: Close-e-garey
RPO: Tailor (John)

No: 631
When Baptised: 14 March 1875
Child's Christian Name: Sage
Parent's Name: Father: John Callister - Mother: Louisa Cain
Abode: Close-e-garey
RPO: Tailor (John)

The RPO is tailor -- the S and the J on Sage's baptismal record differ significantly from the T.

The problem remaining is the document correlation re: John's birth date, I can find nothing factual to base an explanation on. That might lead to Sylvia's suggestion re: John reducing his age to woo/please Louisa, but I doubt it. Kew is only a stones throw from Close-e-garey: John and Louisa lived in far too small a community to carry off that kind of deception.

Far more likely: John was illiterate. The instruction on the 1911 form actually reads: "(To be filled up by, or on behalf of, the Head of Family or other person in occupation, or in charge, of this dwelling.)" I have previously ASSUMED John to be the person who filled in the form, but on closer inspection that might not be the case.

The one document I still haven't tracked down - if it exists - is Wm Callister's will: finding that would be useful.