Hi again, Koromo,
Last week I had half a dozen separate look-ups for various people, and one out of those was unsuccessful. This week again I had six or so requests, and the bad news for you in sunny Cyprus is that yours was the one this week that yielded hardly anything in the way of fresh results, I'm afraid.
I suppose hoping that one could look in the parish registers for Wisbech St. Peter, where James Martin was living in that Census, is rather wishful thinking.
I did indeed look in the Wisbech St. Peter Parish records, but could find no reference to a marriage, or baptisms for any of those MARTIN individuals (children and possibly grandchildren) that you listed.
I also looked for that period in Boyd's Marriage Index for Cambridgeshire, and found only 2 possibly entries for a James MARTIN:
An 1805 marriage to a Mary Waters in Coveney in 1805, and
an 1809 marriage to an Elizabeth Edwards in Wicken in 1809, though this last would probably be too late to fit with a child, Ann, born in 1806.
Perhaps if you can get hold of this family in the 1851 or later Censuses for Cambs., there might be details of where exactly they were born (and raised).
Extremely sorry,
Keith