I could not find them in the 1891 census either. In the 1881 census Robert's birthplace was "on the ocean", Sarah indicated Hayeforth, York about 1828, nor could I find the son Samuel Johnson b. Shildon, Durham about 1862 in the 1891 census. I did find a Sarah Johnson of the right age in Sunderland on Golden Alley but no marital status given and her place of birth was indicated as Sunderland. These are just simple searches there could be spelling errors and the like. Janis