Find Ancestors

Hello I wonder if any one can be of some help to me. I am trying to find information on my great grandfather Charles Johnson. I believe he was in the merchant navy during which he may have lost some body part possibly an eye. I spoke to the merchant navy records office who said that records between 1913 - 1918 were destroyed 'for unknown reasons' in 1969. His first wife, Ann Taffs, died at a young age from pneumonia and there is some speculation that he may have remarried perhaps around the year 1923. That year is a very rough estimate though. There is talk that he and his new wife lived in a 'small holdin' which, i'm told, is a type of small farm. They had some animals. He may also have been related in some way to Amy Johnson - The pioneer airwoman. Possibly an uncle although he was the balck sheep of his family and probably didn't have much of a relationship with them. I'm wondering if perhaps his fathers name was Andrew Johnson and then perhaps his brothers name was John William Johnson. I really hope someone out there can help. This family mystery has haunted us for decades.