The reason I ask is that none of the censuses that I've looked at have the elder William listed as William J, whereas the son is listed as William J(ohn) in both cases (from 1911 free index). Also, on the free index, Susannah S(ophia) is away from home.
In 1906, young William J would be 7-8 - maybe he was M(aste)r J W Richards. Formal titles were usually used in letters, etc. in those days (even in the 1950s, when I was a lass, I can remember writing to a cousin as Master ................ )
Maybe something in the messages on the postcards might help to identify the sender and the receiver.