Thanks very much for your interest. There is a family genealogy for the Bobrinskoy family in a footnote in the Bobrinsky Wikipedia site. I am listed there near the bottom (George Shepherd). My grandfather was George Bobrinskoy, and he grew up on an estate near Toula.
Any further ideas on how tall Catherine was? My daughter, Sophie, is somewhat short, and she wants to know whether Catherine was short too.
Thanks for the help.