Currently on the GWR▸ network we also have Pembrey & Burry Port as well as Ferryside but the website of the FSBPS (Ferryside Signal Box Preservation Society) advises that these are due for decommissioning in March 2024. I think we can also add, albeit in the Summer months, Whitland to the list which is served by Pembroke Dock services.
Dave
Not much in the way of semaphores left at Whitland now. The bay & branch semaphores were replaced with colour lights a few years ago, and the main line signals have been colour lights for decades*, so AFAIR the only old-school signals now are the ground signals. The fixed distant boards on the branch at least provide semaphore pictograms though!
Given the box is relatively new (1970s - albeit secondhand?) were the main line running signals always colour lights? Given its relative youth, perhaps Whitland might be one of the last mechanical boxes to go hand over to Cardiff.