Blue Oval Service Entrance Door (Storage Room)

To provide secondary or service-level access to the Skybase, particularly for maintenance personnel or unexpected arrivals. The door's presence in the storage room suggests it may be used for material transfers or emergency egress rather than standard entry.

The door becomes a critical plot device in exposing the Doctor and Jo's unauthorized arrival, transforming from a mundane architectural feature into a symbol of their compromised position. Its identification as a 'tradesman's entrance' foreshadows their discovery and the Skybase's rigid social stratification. The door's obscure location in storage marks them as intruders in a system designed to control movement.