The strange wagon the shunter is coupled to has lettering EEC Ltd so I wonder if this is an English Electric vehicle for testing and the shunter is ex-works being tested?

Justin Edwards says "There were several wagons at Eastleigh used for static engine testing. Most were based on tender underframes. Looking at the cutouts in the frames they may be ex LSWR. The body is similar but not identical to another vehicle, DS3202 but this used LBSC tender frames "