PMQs Verdict: Hoping for Tory self-destruction is a losing game

On a purely presentational level, Harriet Harman's performance at prime minister's questions today was very effective.

Her attacks on Cameron for "gloating," throughout the session were accurate and fair. As usual Cameron's manner during PMQs was of the school bully who's somehow been put in charge of the class. If Labour had hoped election victory would mellow the prime minister they will have been disappointed.

By contrast, Harman came across as a disappointed but reasonable parent, calmly telling off an unruly child in front of his friends.

"He won the election," she chided to huge cheers from the Tory benches. "He's the prime minister. So he doesn't need to do ranting and sneering and gloating, he can just answer the question. Frankly he should show a bit more class."

It didn't work of course. Cameron's default response to any question is to gloat. It's hard for anyone to change the habit of a lifetime. It's far harder for Cameron to change his habit of gloating when he's suddenly got so much to gloat about. However, by pointing it out, Harman dimmed the impact of Cameron's attacks. It was an effective tactic for dealing with him and shows why, at her best Harman is a much better debater than her predecessor.

Yet on the substance, Harman was far less effective. She devoted the majority of her questions to asking the PM about the process of holding the EU referendum. While it's tempting to assume the leader of the opposition believes the voting franchise and purdah rules are the most important issues facing the country right now, it's far more likely that she had other motives for doing so.

Without a permanent leader and any clear idea yet how to get close to winning the next general election, these are very dark days for the Labour party. With such little idea how to beat the Conservatives, they have been reduced to hoping that the Tories will somehow end up defeating themselves.

It was this hope, rather than any genuine concern about election spending rules or expanding the election franchise, that motivated Harman's questions today. Labour hope – with some justification – that the Tories will soon tear themselves apart over Europe. This may well happen, but then it may well not. It is a losing approach for Labour to base their entire political strategy on it.

Unless Labour can find a better strategy than merely hoping for the Tories to self-destruct, Cameron is going to have plenty more to gloat about over the next few years.