Hope that goes OK Steph. No rush with the pictures so far as I am concerned, have plenty to deal with, like resurrecting my address book after failure(apparent) of email company! Funnily enough I worked at New St. Station from 1991 until 1993 as traincrew personnel officer, but that of course was lomng after he retired. There were still cleaners (now called trainmen) when I was there. Eyesight was the main cause of failure for the footplate grade amongst older drivers. Earlier when my Dad was driving the main cause was diabetes, he was the first driver ever to resume full mainline duties after diagnosis that was in the late 1950s. Now, it's routine, latterly when working on the East Coast route, I had at least 3 men all suffering from fairly severe diabetes which would have certainly terminated their careers in earlier times driving express trains daily at 140mph.
Regarding your grandad, there were two groupings, the merger in 1923 which produced 4 mainline railway companies in the UK, and Nationalization (State ownership) in 1948, the Great Western was the only company to retain its name in 1923, became Western Region of BR.