This route provides an extension to the ECML: London to Peterborough route and adds additional track and scenery to Letchworth Garden City and Royston, along with the EMU sidings at Letchworth and the new flyover at Hitchin.
This extension was done after a request from a friend to include Letchworth Garden City on the ECML route so I initially decided to have a crack at that part.
After subscribing and allowing installation of the route via the Steam Workshop, the route will be listed under Quick Drive as '[DPS] East Coast Mainline - South'. A very basic quick drive has been provided with fast line paths to and from the new stations. Initially the grand plan was to add the new paths to a clone of the original ECML quick drive, but doing so (rightly) fails the workshop validation process. If the route doesn't show up after installation, all I can suggest is to unsubscribe and re-subscribe to the route, I have no control over how the route installs on to your system.