Circle route
In the 1970s most of the suburban passenger network in Glasgow was being converted to electric operation, and the electrification of the entire West Coast Main Line was being planned. Following completion of electrification of the Hamilton Circle route, the line from Motherwell to Lanark was electrified on 6 May 1974, the same day as the start of full electric passenger services between Glasgow and London. At that time the Argyle Line had not yet been constructed, and the trains ran to Glasgow Central.