The pair return from Skeggy -the lights are on.
Pip Dunn and he has a record of the pair working a Walsall-Skegness and return ADEX on 12/08/79. There is no record of the pair working together on any other trains, thus, the conclusion is that this picture was taken then. The return train left Skegness at 17.41 so would not have reached Walsall until afrer 21.00 and thus the ecs would not have got back to Derby until after 22.00 so probably this is not that. Is it possible that this picture was taken early in the morning of 12/08/79 and shows the ecs arriving into Derby station from Etches Park before running round in platform one and setting off for Walsall.