Gordon, I had another look for a baptism on the IOM for your James Wade b Sept 1838, son of a William Wade. I searched on familysearch for illegitimate James Wade births and I came across a very strange entry. I’ve attached the parish register image and I’ve sketched my version of what I think is the original writing which is partially concealed by later overwriting.
Have a look at the original page rather than the version I’ve attached, in order to get a really good image to scrutinise.
To find the image on familysearch, input just “James (no surname) birthplace Patrick, Isle of Man, 1839-1839”. There are several versions for James Robinson; scroll down to the version with just James no surname and click on the black camera icon on the right. Study the whole page first and you’ll see that some of the entries have been amended by someone using a wide-nibbed pen and pale ink. The amendment to James’s entry at the bottom of the page seems to have been designed to render the original entry illegible; I think it may say “father unknown”. But the original words are partly legible. The word illegit is also added in the paler ink.
Perhaps I’m making something out of nothing here, but see what you think.
If I’m right and it does say “William Wade, mariner”, then you could have a scenario where Isabella Robinson took her child, James, to be received into the congregation in Kk Patrick (having already had him baptised privately in Arbory) and telling the parson that the child’s father was William Wade, mariner. But then either WW found out and insisted that he wasn’t proved to be the father, or one of the church officials wasn’t satisfied that the entry was accurate and so amended it and included the word illegit.
This might all be a wishful-thinking red herring.