Nothing much more to add really but is intriguing and irritating!
Going back to Maureen's detective work at reply 25 which all seems to fit, the civil records (not sure they have been posted in the confusion

) show:
Marriage September 1852
James Chaloner and Ann Sinker
Birth December 1852
Henry Challiner
It all looks to be in order- mum and dad married prior to baby's birth.
Bishops Transcript of baptism shows both parents.
Parish register shows both parents.
We will have to wait for the birth certificate full details.