The caption supplied with this negative says E6022 with Parcels train in July 1964. Well the date is clearly wrong as the loco and vans are all in rail blue with the loco having full yellow ends. Date more likely July 1974.
Both the EMU's in the distance appear to be in Blue / Grey livery. The loco is indeed E6022 ( 73116 ).
Location is Gatwick Airport looking south, you can see the runway trip wires either side of the railway. the track layout here has changed a lot the sidings reduced and the wooded area to the left is now under tarmac as part of the airport car park. It is thought the train could be the 1135 Chichester to Bricklayers Arms, this train picked up salad and other fresh produce from various stations along the West Coastway route.
Photographer unknown.