Thanks, Hugh. I had not picked up on son John. What's your source for him? I have found Henry and James on the 1841 census but neither John or Charles; they may have been living with relatives and enumerated under another surname.
I found James, Charles, Charlotte and Ellen in the Parish Registers for North Waltham.
I also descend through Henry's son James, then James Albert, Arthur James and Eleanor Knowles.
Henry's first marriage came from the HGS Marriage Index. Let me know if you have any questions and perhaps we can share information to fill in some blanks.