Perhaps worth noting that Carmarthen drivers go to Pembroke Dock and the southern half of the Heart of Wales line... so to complement the 175s on the expresses and early/late locals, there are lots of 153s, which are well-known for the cramped second cab.
Although interestingly if you read the judgment it was suggested that the smaller second cab is actually more comfortable, at least for some drivers. I know full well that the Carmarthen drivers operate a lot of 15x and 14x stock (five years of journeys to and from west Wales!) - my point was that it seemed slightly strange that these problems had not been manifesting themselves in the many other areas of the country where drivers principally work these forms of traction (
FGW▸ and Northern local drivers, to name but two).