<sigh>
At this point I'm going to say that Track Basher has won, even though the correct answer is still at bay. He has correctly determined that the station is somewhere on the Pembroke branch, and in theory could just post all of them one-by-one (more than one without a reply is cheating, as I've found out the hard way before now...) until he calls it, as has been true of the last few. So, to save time, the correct answer is...
Kilgetty