David Cameron saved the best till last at today's PMQs. He seized on the leaked PMQs memo (£) in today's Times and taunted Ed Miliband with its contents: "It's important to have a cheer line." Having used up all six of his questions, Miliband could only grin as Cameron landed an easy slam dunk.
The Prime Minister finished: "He's got a plan for PMQs but he's got no plan for the economy, no plan for the debt." That alone was enough for him to claim a points victory.
But that flourish followed a fierce exchange on the housing benefit cap in which Cameron offered no hint of compromise – a stance he may live to regret. Miliband's joke that a glum Nick Clegg "was back on the fags" may have fallen flat, but he was right to draw MPs' attention to a glum-looking Simon Hughes.
Hughes, who has warned that ministers will have to "negotiate" to win approval for the "draconian" measures, will be alarmed by Cameron's obstinacy. The Prime Minister's repeated insistence that "we're sticking to our plans" throws into doubt the possibility of transitional arrangements for London, as demanded by Boris Johnson.
It was left to the Lib Dems' serial rebel, Bob Russell, to sound a note of caution when he warned that the subject was "no laughing matter". Should, as charities warn, 82,000 families be forced out of London – the largest population movement since the Second World War – Russell's words will prove prescient.
Regardless of the rights or wrongs of the cap itself, the population churn will overwhelm local councils. Expect calls for compromise to spread to the Tory benches in time.
Miliband's performance had improved noticeably since last week and his urge for Cameron to "think again" about housing benefit will have resonated with Lib Dems. He and Labour will have many more opportunities to exploit divisions on this issue.