The order that the family was listed in 1841 is intriguing, not quite as shown by Ray:
James 30
James 10
Mary 25
Henry 7
Emma 2
Eliza 5 mths
I've seen cases where all the males are listed followed by the females, but the position of Henry makes a mess of that possibility.
Another interpretation is that Mary wasn't the mother of James jun, but that he was from a previous marriage (possibly the one at Edmonton on 6 Jun 1830 between James Mardel bachelor and Mary Ann Bird spinster). James and Mary had a son James Mardle born 15 Aug 1831 at Eaton Place. They had a daughter Mary Ann on 22 Feb 1833 which, if there were two marriages would put the marriage at c1832 (although I suppose that Mary Ann Bird could have died almost immediately after the marriage and James remarried rapidly in time for a child to be born in Aug 1831). But I can't see a burial of Mary Ann nor a second marriage, and the timing all looks pretty tight. But as you have a birth cert of one of the younger children where the mother's maiden name is listed as Roberts, and the presence of John Roberts tends to confirm this, then two marriages seems the most likely explanation.
There are a number of John Roberts baptisms in Beds at around 1776. It will take some work to try to narrow them down, and even then it will be difficult to prove conclusively that it's the same John Roberts who lived in Edmonton. And more work again to prove that Mary Mardell was the daughter of John Roberts, as without her marriage and her baptism you have a large disconnect.
Running two parallel threads without a cross reference is a recipe for duplication of effort
David
