It’s a strange thing but you tend to imagine this diagram hasn’t ever changed but Harry Beck, the creator of this version, was often evolving the look and style – sometimes for better and sometimes for worse. In this 1954 version many of the outer branches changed shape and overlal the depiction of the lines themselves were thickened up and overall it made the map look a bit ‘clumsier’ than previously.

via Flickr https://flic.kr/p/2ch1Z6F