There must be scope for a through train service between Exeter, Taunton and Weymouth, reversing at Castle Cary. Possibly an experiment could be run in summer with one of the 'mini HSTs' soon to be created with the coming of the IEP. I remember from my youth some BR literature concerning travel between Devon and Weymouth, and a footnote saying that as the train from the Westcountry didn't stop at Castle Cary, people had to go via Westbury and to pay a higher fare, which struck me as rather stingy! It does show a potential demand.