The large, heavy, leather-bound volume called "The Chester Division of The Great Western Railway 1924-5" – which may be the only copy left – gives information about every station, halt, platform, siding and junction, and the "principal residents" of the district served by each station, along with their addresses.
The story of its rescue is told in the trust's newsletter, Abbey Lines, which describes it as a treasure chest of fascinating information.
Among snippets are that Leaton had a staff of seven and receipts from passengers amounted to £547, and Gobowen had a staff of 26, including a female gatekeeper, although no "principal residents" are listed for the village.
As well as familiar titles such as station masters and signalmen in the staff lists are some forgotten roles, such as "slipper lad," "caller off," and "call boys."
Terence Turpin, chairman of the trust – which aims to raise awareness of the railway heritage of Shrewsbury and the region – said: "The book was discarded when there was a regional boundary change in British Railways structure.
"The London Midland Region took over a large area of Western Region territory in 1963 which included the Shrewsbury area and the commercial department moved back to Chester after a period in the newly-built offices in Chester Street, Shrewsbury.
"I worked in the same office block, but in the civil engineering department, and spotted the book in a pile of rubbish that was not intended for transfer to Chester, and I saved it from oblivion.
"The book is not a publication for the general public but for internal use only and is probably the only copy in existence."