Brilliant thank you both.
As you say Heywood civil and church records are a year apart and seem to have different fathers, neither of whom were present at the birth (Gallagher was)
But, looking back again at the marriage record you posted right at the start, of James Ferry and Mary McFaddon, Feb 1867 is consistent with a birth in Feb 1868 to match the civil record. This record includes (as you pointed out) a Michael Ferry as sponsor and a Neil, which have variously ended up in the different records in Derry. So I suppose all those names might easily have just been given the wrong relationship if they weren't known in Derry.
//www.irishgenealogy.ie/files/civil/marriage_returns/marriages_1867/11484/8221225.pdf
Nelly who has been mentioned before, was born in 1864 to Michael Ferry and Mary, formerly Ferry - maybe it was the same Mary McFadden, although this would have been before they were married. Nelly did seem a close family relative, was known as 'aunt' Nelly.
//www.irishgenealogy.ie/files/civil/birth_returns/births_1864/03616/2334520.pdf
There was a story about one of the Ferrys going to Scotland then the States. This might shed more light. Perhaps James and Michael were away at various points. This would explain seemingly no more children for James after 1868.
There was a Brendan John Ferry perhaps born in Scotland who went to America. He died without family and the family over here didn't know him or know about him, but they were contacted about an inheritance I think. Maybe he was a son of James or Michael. I haven't been able to find him so far.
There is a Michael Ferry who died in Hamilton, Scotland in August 1927 who was from Brinlack. I know there was a Michael, son of Michael Ferry and Cecilia McBride born in Brinlack in 1870. Maybe it was him. I think he had a brother Jacob born in 1870.
https://registers.nli.ie/registers/vtls000631955?locale=en#page/104/mode/1up
