Thank you for all the replies and suggestions. The arrival of my Samuel and Josiah was in January 1855, not January 1852. However, I have had a sneaking suspicion that the Samuel who arrived in 1852 may have returned to England to entice his brother to join him in the new country. On arrival Samuel may well have returned to SA as he may have established a life there on his previous visit. Josiah, on the other hand, remained in NSW, married and had a family, his sons being Josiah and William. From what I can gather from NSW BDM records, there were two births for Josiah, so I assume that the first one died in infancy, and then along came my grandfather.
Rhonda, in the book it is interesting to note that Samuel was a plumber. I didn't know that profession even existed at that time, but I guess they still had to install pipes for water, etc. I do know that my ggrandfather, Josiah, did not maintain his profession of Stationer, as he became a farmer. Anyway, I shall just have to get out the shovel and 'keep digging'.
Narelle