What is being done this year is a compromise taking into account the lack of GWR traincrew route knowledge west of Carmarthen, which will not be regained in time to run summer trains to Pembroke.
On Sats from 22nd May to 11th Sept inclusive
0929 Swansea-Carmarthen (arr 1012) is an additional service.
Connecting into TfW 1055 Carmarthen to Tenby (1140) and Pembroke Dock (1219).
0848 Paddington-Swansea is extended to Carmarthen (arr 1230).
Connecting into TfW 1258 Carmarthen to Tenby (1343) and Pembroke Dock (1418).
1539 Swansea-Carmarthen (arr 1622) is an additional service.
Connecting into TfW 1700 Carmarthen to Tenby (1745) and Pembroke Dock (1820).
1122 Swansea-Paddington starts back from Carmarthen at 1032.
Connects out of TfW 0909 ex-Pembroke Dock, Tenby dep 0939, Carmarthen arr 1026.
1726 Swansea-Paddington starts back from Carmarthen at 1636.
Connects out of TfW 1509 ex-Pembroke Dock, Tenby dep 1544, Carmarthen arr 1629.
The workings appear unbalanced because there is an ECS leg off the 0848 ex-Padd taking the stock back to Swansea for servicing prior to the afternoon trip. All the above call at Llanelli and Pembrey & Burry Port en-route between Swansea and Carmarthen (or v.v.)
If you’re not keen on using the TfW connections is there any practicality in using the GWR services as far as Carmarthen as a railhead for your destination in West Wales, perhaps hire a car from there or similar?