Thanks again for your rapid response.
Please take a peek at this: http://o.mfcreative.com/f4/exports/f/f82840dd-0d83-446c-9edc...
We believe that Alfred's mother was Emma Tennick. He was raised as a Roman Catholic, so that should narrow things down a bit. As I said previously, (Alfred) George William Johnson used the name "George William Johnson" while/whilst in the U.S.A. I have never been able to identify a birth certificate--only an indication of a May 1881 date of birth.
(Alfred) George died at New City, New York, Rockland County, U.S.A. on 09-May-1934.
P.S. Regarding marriage on the ship--the ship manifest uses Johnson for both parties as a last name. Perhaps they never were married. Who would know? They both conveniently lost their birth certificates.