"Walter John Waller, grocer and draper, Blundeston" appears in the 1912 Kelly's Directory under Commercial. The address is not listed.
The Enumerator's list for Blundeston on the 1911 Census has "The Street, Shop and Dwelling House, Waller" and the Census return reads "Walter John Waller, Grocer and Draper".
Have also checked the 1921 Census but details cannot be disclosed. It does provide a fresh "name" to search.
I'm assuming "High Street" on the 1891 Census is "The Street" on any later Census.
Have you checked out the photo you hold on Streetview to see if the building is still there? From what I can see from the Census it was at the "Short Road" end of "The Street".