Sanderson & Grainger

Sanderson & Grainger was a department store, located in Colchester, at which the Eleventh Doctor once briefly worked. It was located directly over a small Cyberman base, and was infested by a "silver rat," in reality a cybermat. The Cybermen there were culling the store's staff, whose body parts were then cyber-converted.

People known to work there included Shona, Kelly, George and Val. (DW: Closing Time)

Behind the scenes
The name likely partially refers to Ernest Grainger, the original head of the men's department at Grace Brothers, the fictional department store seen in Are You Being Served?.