Hi,
Welcome to the Forum.
Reading this section will explain most of what you want to know:
http://www.925-1000.com/dlSheffield.html" onclick="window.open(this.href);return false;
What may confuse you is the apparent striking of two maker's marks, the maker is Walker & Hall, and John Edward Bingham (George Walker's nephew) was the senior partner of that firm. He took control of the business and entered his mark at the Sheffield Assay Office, both in 1873.
Trev.