Finally, yes, t'was indeed Welshpool to Aberystwyth on a ATW 158.
Answers to the questions for those who care.
1. Welshpool is now a modern bus shelter station with the proper buildings next to the station now occupied by shops.
2. Cambrian Coast Express
3. Aberystwyth station buildings now hosts a Wetherspoons
4. ATW only.
5. English and Welsh
6. 7 open, 12 closed
7. 3 times
8. Cambrian Mountains
9. Trains split at Machynellth, one portion heading to Aberystwyth, one to Pwllheli
10. It is.
11. The Old College building (gothic building on the seafront) was orignally meant to be the station and railway hotel, it never happened and it is now a part of Aberystwyth University.
12. Aberystwyth is the location of the National Library of Wales, one of the UK's copyright libraries.
13. Members of the Welsh Language Association blocked Trefechan Bridge in Aberystwyth in 1953.
Bakers dozen of clues and over to dzug2.