Hello Roses Lass,
How good to hear from you.

I'm pretty sure I found William Wilcock on the 1851 census.
He was living with a family called Taylor, in Holme.
The reference is HO107/2441 Folio 630 Page 19
The head of household is a Richard Taylor, stonemason.
The reason I'm convinced, is that one of Richard's sons is a Christopher Taylor, about William's age, who happens to be one of the witnesses at Williams marriage to Agnes.
Also, on the 1841 census, there is a Margaret Taylor living with the Wilcock family in Holme.
I haven't been to prove a definite link, but it's suggestive isn't it?
As for Agnes and her father Edward ... I'm in the dark.
The Read/Postlethwaite families seemed to live near to each other in Captain French, but no sign of Edward.
His wife Mary is shown as a widow in 1851, but as yet, I haven't found a death/burial for Edward.
Yorkslass