47489 Exminster 22 April 1988

47489 heads south at Exminster on 22 April 1988. Nowadays, with readily available gen, no train is unidentifiable, but in the 1980s, with no mobile phones or sources of information, things were very different. This clearly looks like an inter-regional train, but there was nothing scheduled anywhere near the time (17:00). Any information would be gratefully received.