Hello, and firstly my apologies for leaving you in the lurch without a reply. I am afraid have have been forgetting to check the Rootschat site for ages.
Robert Stephenson and Mabel Carr are not linked to me in any way - My Stephensons are not far away geographically, but I don't think there is a relationship. My Marmaduke Stephenson hails from the East Riding of Yorkshire, and came from a long line of farming folk. Sheep, I think.
If I learn anything else at all that helps to shed some light, I will of course let you know.
Thanks very much for writing, and once again my apologies for seeming ill-mannered.
All good wishes,
Francis Wright (direct descendant of quite a few Marmaduke Stephensons!)