Bob Allison
I bought a secondhand copy of British Railways Track for £50 a few years back and for a while it was the best reference I had. Then I discovered “LMS Drawings of Standard Railway Equipment – Permanent Way” which is freely available at
https://www.lmssociety.org.uk/downloads.php
and the equivalent LNER version which can be purchased from the North Eastern Railway Society. Either of these is much, much more useful for modellers of bullhead track than BRT and massively cheaper. To be honest, the majority of BRT is not really relevant to us modellers, being concerned with maintenance procedures and formulae/tables for setting out curves and junctions.
None of this will be much use to James who is modelling GWR track, but may save modellers of other persuasions unneccessary expenditure.
Bob