There were no letters on file from the 12th to the 17th of July 1916. However there was one letter which was undated and it looks from the content as if it was written at Camp Borden, perhaps early in Dick's time there. From the letters after the 17th, it looks as if Dick may have journeyed back to London Ontario on a leave of absence.
The reader will also observe that Dick comments on how his wife "isn't feeling well". The family and I have discussed this and it seems she was expecting her third child and perhaps was experiencing "morning sickness".
I've also included a clipping from the Globe on the 12th of July 1916 wherein the L Col of the 142nd makes it quite clear that "London's Own" had nothing to do with the booing of Sir Sam Hughes.