O.S. Nock continues his account of the GWR 4-4-0s with a further look at G.J. Churchward and his programme of modernisation and standardisation, particularly in boiler design, and his introduction of the 'County' class - the last of the new GWR designs. He goes on to describe the impact of two world wars; the implications for the 4-4-0 classes post-Grouping, with particular regard to the Cambrian section; the start of withdrawals in the 1920s and the introduction of the 1930 hybrids, nicknamed the 'Dukedogs'. Nock's trademark detailed text, accompanied by copious photographs and locomotive layout diagrams, includes run logs and his descriptions of footplate trips including a notable one made on City of Truro.