I'm trying to trace a Conrad and Dorette Jahns. My great-grandfather Conrad Henry Frederick Jahns came to England sometime before the 1891 census. I only have the information on his wedding certificate, a silver wedding card from Familia Jahns, Grasdorf and a card notifying his death to a Frau. Dorette Jahns at Bischofshoberdam 7, Hanover. Any help as to where I start looking would be gratefully appreciated!