It is dusk as the light is on in Exeter Middle Box.

David J. Hayes says "Although approaching from the north, the headcode would imply that this is an overnight milk service to London; from Torrington, perhaps? In the past many such workings to London would have ran to Kensington Olympia from where the milk would have been distributed around the capital by feeder services. By 1972, most of London's milk traffic was being tripped from Acton Yard".