Okay, I'll check the PR re: John & Louisa's marriage record to see what it says.

I can't find any census records for John James b.1843/44 m. Elizabeth Clucas 1866, but there is a death record - CALLISTER, John, 25, German, 30 Jun 1870 - which might explain his absense.

There is a John Callister 1871 England census, Tranmere, RG10/3751:

John Callister, Head, Mar, 31, Joiner, Isle of Man
Elizabeth Callister, Wife, 30, Isle of Man
Elizabeth Jane, Daur, 8, Scholar, Isle of Man
Frances, Daur, 5, Scholar, Cheshire, Tranmere
Ada, Daur, 3, Cheshire, Tranmere
Frederick, 1, Cheshire, Tranmere

But he's born circa 1840, & Elizabeth 1839.

There is an Elizabeth Clucas c. 6 Dec 1840, Patrick (C038241), but there's also an 1851 IOM return (HO/107/2523) which states John J son of Wm & Amelia as born abt 1844, which tallies with the IGI.

Is the 1871 return John J son of Wm & Amelia? Can it eliminate Wm & Amelia as our John J's parents?