The shop housed a Petrichor advertisement, with Amy Pond as its model. 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.
Behind the scenes Edit
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 the sitcom Are You Being Served? (1972-79, 1981, 1983, 1985).