I have been having a bit more of a play.
Firstly, James Gill who married Ann Clarkson.
I stated earlier that his likely bp was on the 3/1/1792 to Jonathon and Mary of Silsden, a labourer.
The most likely of marriage for his parents was this interesting find :
Jonathon Gill of Silsden, husbandman, bachelor, to Mary Clarkson of Silsden, minor at Kildwick on the 8/12/1788.
Another find was for James and Ann's son Thomas who I have listed earlier as born 1822 (the one I stuffed up the date

)
This could be his family I found in the Memorials (headstones) for burials at Silsden.
In memory of three children of Thomas and Margaret GILL of Silsden, Fanny died May 16th 1851 in the 5th year of her age, William died July 6th 1851 in the second year of his age, and James died June 9th 1852 in the first year of his age.
Also the above Thomas who died Oct 14th 1852 in the 30th year of his age.His age fits nicely.
Thought perhaps the name Dugdale might put some light on to the Ann Clarkson, not many in Silsden at all and I cannot see any link into the Clarkson family.
Also thought might try to follow up on the name Nanny in case of family traditions in naming. Not too many clues but will pass on a couple I found
Nanny Clarkson - dau of William and Mary Ann of Silsden, a masons labourer, born 1880
or Nanny Clarkson, of Silsden, widow, died 11/1/1771
Might have family ties but cannot say for certain.
I have also some possible siblings for James Gill born in 1792, but the occupation changes for the father so not sure if the same Jonathon or another. I can give you these anyway if you wish and I will list the occupation with it so you can decide for yourself.
Hope this is of some help to you
Margaret