Hi, I have to agree that Leonard is probably a sibling who perhaps died young. One day maybe we will discover who he is.
I have two Thomas's in the tree but neither are the one you are looking for. I didn't find any other connection with the Dudley line as yet but as I am sure there are probably a lot more Dudley's out there who I have yet to discover it is possible that one day I will find the link. I have about 1800 Dudleys all from the same branch.
If I find anything new I let you know. Best wishes, Claire