Thanks Donna.
Overnight I've been thinking. I was hasty to assume that William, father of Isabella, was brother to John Quayle.....as his wedding cert. named his father as William, I SO wanted him to be John's brother.
But really, dates don't fit...William is rather too young for this to be a match.

Also I need to remember that John's wife, Margaret's maiden name was Quayle...so he could just as likely belong to her side of the family.
She was born in Braddan, I believe the d. of Wm Quayle and Catherine Hampton, christened Sept. 1793....But I can't find a son, William!
Margaret married John Quayle, Marown 1819.
William married Ann 1838, Patrick.

Wm Quayle and Ann, parents of Isabella etc. both died Patrick. Wm left a will on Lawson's site. Aug 1887. Census states Engine Driver, so fits.
Ann died July 1885....no mention of her death in Brian's list, although I have the Patrick M.I. book, and her name, Ann Anderson, is on headstone with Wm.

When I'm on island I 'll have to look up actual record of John and Margaret's wedding, and hope for his father's name to be there.

Could do with staying over for a month!