Thank you for your helpful suggestions, Sue.
My quest was to find the baptism and birth parents for James Thomson's wife, Ann Caley, who gave her father's name as John Caley and her birth parish as Ramsey.
To try and summarise what we have:
1) If Ann's birth was legitimate, and if her birth parish was indeed Ramsey, then the only baptism in the IGI which fits is the 1853 John Caley/ Isabella Corkill one. She'd have been the 8 yr old "Margt" at Port e Vullin in 1861, but not yet identified in 1871.
2) If Ann's birth was illegitimate, then she could well have been the 14 yr old Ann Caley servant b Lonan with John Corkill in Maughold in 1871. But it would be very hard to identify her in 1861 if she'd been listed with her mother's surname, or the surname of a stepfather.
I admit defeat on this one, which is a shame because Ann was the great grandmother of George Harrison (singer/songwriter) and it would have been nice to trace the Manx bit of his ancestry.
Jean C