Cathie,
I don't know if the enumerator who took the details from the Douglas family for the 1841 census in Cramlington ( page ref 824/1 24-42 ) was inefficient or was fed incorrect info by the family.
If son Selby was born in Tweedmouth ( enumerators could use " parish of birth" or "place of birth" to complete the " Where Born" column) as some later censuses indicate- although Ancroft and Chevington also get recorded- then the answer to the question " whether born in this county- or not" should be "N" for no.
Right up until 1844 the whole parish of Tweedmouth, and that of Ancroft and others were County Durham, not part of Northumberland. Collectively referred to as North Durham.
Also enumerators were instructed to record the ages of those 15 yrs old and above, as their age rounded down to the nearest multiple of 5 years. So if Selby was 18 yrs old, he should have been recorded as "15" ( and Elenor as 45, David 15)
On the 1841 census, James at 20 years is the youngest child in the household.
Was in fact James the youngest child or had John/Elenor had earlier children ?
I notice that some Ancestry.com transcriptions of the family on 1841 are showing info ( i.e. birth places) which are not gleaned from the actual census.
Michael