An excellent book, well done Jim. I received my pre-ordered copy earlier this week, direct from the publisher. It really does bring together a lot of material from different souces so will be very useful. The shaded line drawings are excellent, particularly in tracing changes during the evolution through various diagrams of a particular class. I did find one small comment that needs attention, a reference to Saint David's conversion to the prototype Hall on page 126. It was of course 2925 St Martin that underwent conversion in 1924 to become the first Hall. 2920 St David was the last Saint, being withdrawn in 1953. Most GWR afficionados would be well aware, so would regard this as just a minor slip that occurs easily at the editing stage.
The section on tenders is particularly useful, as alluded to elsewhere.
David Murrell