Are the GWR Castle Class services not reservable? They are marked as reservations recommended on RTT, but TrainSplit doesn't seem to be able to offer a reservation on the service. For context I'm trying to reserve a seat on the 13:00 service from Cardiff to Penzance, travelling between Bristol Temple Meads and Bodmin Parkway, but TrainSplit gives the message:
Same is true for the Castle Class service on the return.The train operating company does not offer a seat reservation for this ticket on this leg of the journey.