That appears the one Francis. as the two = Jane and William, married, I believe in 1810 the only chance would be if they had an Isobelle early in their marriage (forced wedding) and she was baptised elsewhere.

Seems unlikeley.

So, this leaves me with an Isabelle Kelly who.
from the 1851 census, came from the IOM. And from my aunt Elsie who lived in the IOM, and is buried there, she said Isabelle is linked closely to Gick of Cordeman. (But where?) In fact says 'daughter of', along with an Agnes, and Jane, who were Jane Clarkson's aunts.

Isabelle is listed as 'wife' of Joseph Ckarkson in all the subsequent censuses, and they had a daughter in 1833 who is my g g grandmother
as she married James Henry Newton and they lived in the Manchester area.

Thanks for your much appreciated help. I am beginning to feel I will never find the answer.