The London Midland Region was divided into 4 sections: Western Lines South, Western Lines North, Midland and Central.
Western Lines South: This book covered the routes from London Euston to Crewe and Rugby to Stafford (via Birmingham) and related branches. Loosely it can be described as the L&NW Rly. south of Crewe.
Western Lines North: This book covered the West Coast main line from Crewe to Gretna Junction, the Cumbrian Coast route, Crewe to Holyhead, all things L&NW to the south and north east of Manchester, and related branches. Also included sections of the G.C. around Chester and the Wirral.
Midland Lines: This book covered the routes from London St. Pancras to Manchester Central, Marylebone northwards to the regional boundary with the Eastern Region, the Woodhead route west of the tunnel and the whole of the Cheshire Lines Committee. There were also various other parts of the Great Central included, such as the route to Wigan Central.
Central Lines: Think Lancashire and Yorkshire Railway west of the Pennines. The L&NW route from Manchester Exchange to Liverpool is included as far as Newton-le-Willows, as are lines to Bolton (Great Moor Street) and a portion of the Settle and Carlisle Railway.
The Eastern Region was divided into 5 sections: North Eastern Region (Northern), North Eastern Region (Southern), Great Northern, Great Eastern and London, Tilbury and Southend.
N.E.R. (Northern): This book covered the East Coast main line, and associated routes and branches, between Northallerton and the Scottish Border.
N.E.R. (Southern): This book covered the East Coast main line, and associated routes and branches, between Shaftholme Junction (Situated just south of Selby) to Northallerton.
Great Northern Section: This book covered the East Coast main line from Shaftholme Junction to London Kings Cross, associated routes and branches, and lines around Sheffield, including sections of the Midland and Great Central main lines.
Great Eastern Section: The route from London Liverpool Street to Kings Lyn and associated routes and branches.
London, Tilbury and Southend: Self explanatory.
The Scottish Region was divided in 3 sections: Northern, Western and Eastern.
The Southern Region was divided in 3 sections: Central Division, South Eastern Division and Western Division.
The Western Region was divided into smaller areas called traffic districts. The routes covered are pretty much self explanatory.