What are "Long Routes"

A long route is a route that that comprises a series of two or more routes between consecutive signals.

E.g. Signal 1 has a route to Signal 2 which has a route to Signal 3. The long route is between Signal 1 and Signal 3 which is requested by clicking first on Signal 1 and then on Signal 3. This actually calls both routes sequentially and thereafter the routes and signals behave exactly as they would had they been called individually. Each route is requested sequentially so that if an individual route is not available, subsequent routes will not be requested.

This feature is not found very often.

From the glossary wiki page entry:
Quote:

A long route is a route that that comprises a series of two or more routes between consecutive signals.

E.g. Signal 1 has a route to Signal 2 which has a route to Signal 3. The long route is between Signal 1 and Signal 3 which is requested by clicking first on Signal 1 and then on Signal 3. This actually calls both routes sequentially and thereafter the routes and signals behave exactly as they would had they been called individually. Each route is requested sequentially so that if an individual route is not available, subsequent routes will not be requested.

This feature is not found very often.

I'm not sure why Stafford has it, given that the signalboxes in the Stafford area were mechanically interlocked. (Although I think Norton Bridge was a panel by this point).

(Although I think Norton Bridge was a panel by this point).

Yes that is true, the direct route is a bit shorter, but these 'long routes' are not related to diversions. They are a way of route setting in Stafford station (and possibly other places in the sim). You can click any two signals around the station, and if there is a straight route between them the sim will set all intermediate routes for you. You can for instance signal a train from Birmingham to the SL, or a through train on the FL, all the way through the junctions and station in two clicks.