I should add that my suggestion of Exeter to Weymouth has the attraction that it would not involve changing. That is a big plus for pax, especially as there are so many retired in that area. A simple change at Weymouth could then get you as far as Portsmouth if that service was started, or at least to Southampton. It should however be limited stop and interleave with the present stopping services. It does need that cooperation between TOCs though. It doesn't need a new interloper.