9A.21B is LLandilo, "Junction for the Carmarthen line", and the local on the left is the Carmarthen train. Its route will pass through LLandilo Bridge, Golden Grove, Drysllwyn, LLanarthney Halt, Nantgaredig and Abergwili. For anyone lucky enough to have "Steam in South Wales - Volume 2 North and West of Swansea" by Michael Hale, Plate 114 shows the Carmarthen local awaiting its connection in the bay at LLandilo on 29/08/1959. The makeup of the train is fascinating and I have attempted a re-creation using N gauge RTR, probably not the topic for this thread.
Plates 108,109 and 110 show three of the stations on the former LNWR branch and Plate 115 shows the train from Shrewsbury arriving at LLandilo and about to make its connection with the branch train.
As has already been said, this is indeed a marvellous collection, and thanks for sharing it.