He's putting on his best Khrushchev style "The party know best" glare as he applauds, what I can only imagine are, a procession of uniformly dressed young people who have just graduated from Labour's Institute of Correct Thought and Propaganda. The very institute Ms Ellie Gellard graduated from. Only she is supporting his pugnacious leadership opponent, Ed Balls. So, he must hope pictures like this will appeal to that kind of pre-programmed socialist, perhaps winning their first, or at least second, preference votes.
Obviously, he'll need a completely different image when (or rather if) he becomes leader as he'll need to appeal to normal people. I'm sure comrade Campbell is waiting in the wings to deploy his polishing skills on whatever turd emerges as leader.