Right until closure, the line from South Pelaw Junction, all the way to Consett was signalled using semaphore signals although colour light signals were in use on the approach from Ouston Junction from the 1960s.
The subject of signalling is far too complex to go in to on this site but, suffice to say, the North Eastern Region Railway company, who originally built the line, liked complex signals as the photo of the gantry at Stella Gill further down this page shows.
Below is the Signalling Diagram for South Pelaw Junction from 1963 when the South Pelaw Colliery sidings (to the top of the diagram) and all of the Stella Gill Sidings were still in use. The line from the Ouston Junction and the East Coast Mail Line comes in from the bottom left with the climb up to Consett starting bottom right.
The 1970 signalling diagram for Carr House West box at Consett can be found hereand the 1950 diagram for Carr House East here.