This book contains no less than 69 different diagrams of former London & North Western Railway locations drawn in the style of signal box diagrams. The diagrams start with Broome and cover every location southwards as far as Llanwrda. After skipping the joint GWR-LNWR section, the diagrams recommence with the LNWR station at Pontardulais to continue unbroken to Swansea Victoria. The LNWR branches to Carmarthen and Llanmorlais are included to complete the picture.
The diagrams represent the signalling in the period prior to closure south of Pontardulais and shortly before the economics of the 1960s took hold and reduced almost all the double line sections to single with passing loops.