SkyRabbit - read the message properly !
It says that due to the small numbers originating in Plymouth it makes it necessary for the stop in Cardiff .Hence loads from the South west are low and not worthy of another service from the same area .
I totally agree in what you say,Cardiff-Newcastle I believe is the most successful route of 6G .
Believe me ,
I know !
A little hasty in your reply - something to learn for next time !
Cheers