Sanderson & Grainger

Sanderson & Grainger was a department store 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. (TV: Closing Time)

Behind the scenes
The name likely partially refers to, the original head of the men's department at Grace Brothers, the fictional department store seen in.