This is all a joke, no?

My nephew. Alex, is keen on a political career. I can say, with not a hint of irony or intentional humour, that he would make a better Prime Minister than Ms Harman. Alex is eleven. There is not a single issue or judgement call on which I would not prefer to rely on his decision than Ms Harman's.

On the other hand...it's the one way to guarantee Cameron victory, so it has some logic.