Shoko,
Many thanks - brilliant! The appearance of the mother-in-law gives me the maiden name of William's wife Elizabeth, over whom I have struggled for some while. I had earmarked the marriage to Elizabeth Coaks in 1817 at Lytchett Minster as a likely option and you have confirmed it.
I can also locate the second Bartlett family of Charles and you have confirmed his relationship to Amelia, who died shortly thereafter.
Could you - pretty please - look up Willam's brother Benjamin (b. 1796) and his family who were in Almer at the same time? I can't give you the full census reference but they are adjoining villages. I went down there a couple of months ago and even found the farm where they lived in 1841 but no trace of any documentation or gravestones or anything.
Many, many thanks,
Terry