Opened in 1960 replacing two previous boxes at Machynlleth East and Machynlleth West, Machynlleth contained a 50 lever frame and controlled the station, access to the single line sections and an array of sidings and works. In 1988, the box was extended in order to accomodate the then new RETB signalling system, which allowed the entire cambrian lines, a distance of almost 140 miles, to be controlled from the one location. Control of the box was handed over in sections to a new ERTMS control centre from October 2010 until full closure on March 19th 2011.

Diagram of Machynlleth (2009), Drawn by Danny Withington.