50031 1977-02-05 Penzance
With a sizeable gouge in the side.
As the coaches do not have Inter-City on the side they must be vacuum braked Mk2 stock and the lighting suggests the photo was taken in the earlyish morning. Both of these points lead me to state that this working is the 1B83 23.45 Paddington - Penzance, due to arrive at 09.05 .