Hi beanie
It has been suggested that James Mitchell and Agnes Syminton are probably John's parents, which I must admit looks like a fair runner, seeing John's daughter was Agnes. There appears little info about them, though. If you can expand this at all, I'd be much obliged.
Regarding 1841, it would appear not.
However there may well be some connection between the two families prior to coming to Norfolk.
Obviously John Mitchell was first here, marrying in Norwich 1846. He was followed by Duncan McQueen b Penninghame 1840, who married Jane Summerville in Norwich 1869, and then his brother William b 1846 who married the young Agnes Mitchell b Norwich 1854.
As they were all travelling drapers from the same neck of the woods, it has to be a huge coincidence for there to be no link. Why all gravitate to Norwich?
Best wishes
Mark
