The box dates back to the 1960s and is a standard Henry Williams Turn & Push style panel, controlling ten Western Region E10k-type Route Relay Interlockings, and as such does not have TORR.
The area of coverage extends to the fringe with Exeter Panel to the East near Totnes, and across the Royal Albert Bridge into Cornwall to meet Liskeard Signal Box to the West.
Initially covering Lipson Junction to Keyham (exclusive), the panel was extended in 1973 to the fringe with Totnes and St Germans Signal Boxes, and then again to cover St Germans area itself in 1998, now fringing with Liskeard. Although part of the main panel, the extension is drawn separate to the main drawing. It is said that the reason was to allow the engineers to add it without disrupting the signallers.
Although divided into 2 panels, the operation is reasonably simple with most of the action at Plymouth itself and in the St Budeaux/Saltash area. In the morning and evening, Laira TMD sees some action as trains are serviced overnight.
During the early days, this was quite a busy depot with an allocation of Class 52 Westerns and other Hydraulics and later Class 50s with many trains changing engine at Plymouth. The area also saw extensive freight workings of China Clay from Cornwall.
Nowadays the staple diet is HSTs from Paddington, Cross Country trains and local DMUs from Cornwall and the Branch to Gunnislake.