Hmmm.
If Catherine Wharton was born in 1814, then Catherine could not be the mother of a child born in 1828/1829.
There are three births of children in Liverpool, mother's maiden surname Wharton, between 1837 and 1846
Alfred, 1838, December quarter
Agnes, 1841, March quarter (must have died in early infancy as she's not in the 1841 census)
Agnes Lorain, 1844, June quarter
It is clear from the 1851 census that Alfred and Agnes Lorain are brother and sister, therefore they have the same mother, therefore the age listed for Catherine in 1841 has to be wrong. (Even though it is perfectly clear in the original - see attached.) If Catherine Wharton was born on 9 July 1814, she was 26 on census day 1814, and should have been recorded as aged 25, not aged 12!
But if the 12-year-old Catherine in the 1841 census is correct, who is she, and more to the point, where is David's wife Catherine Wharton or Scott?