In this case the train would appear to be the 12.55 limited stop service from Taunton to Ilfracombe due 15.33. However the train started back at Bristol TM at 11.35 due Taunton 12.45. It may even be the 07.50 off Llanelly due Bristol at 11.32
None of these trains were advertised as through trains which they would have been 12 months earlier in Summer 1963.
This was the penultimate Saturday for this train/timetable. The following Saturday, 5 September 1964 was the last time it ran, and the last day of steam for Taunton-Barnstaple. Taunton Shed closed the same weekend.
Thanks for your valuable suggestions Mike.