The really impressive thing about Jeremy Corbyn during PMQs is his confidence. It's not easy to control the Commons chamber. You don't pick it up on TV because only the mic closest to the person speaking is switched on, but the place is a pit of noise, with barracking and mockery coming from all directions. Most people hoping to quieten down the Chamber fail to do so. They wait for a silence which never comes.
Not Corbyn. The Labour leader is earning a reputation as the master of side-eye. At one point he simply stood silently, looking around with disapproval at the Tory benches in front of him until they shut up. And shut up they did. It was remarkable. "Thank you," he said, like a teacher presiding over unruly pupils. He did it by being solid. Any trace of nervousness or weakness and it wouldn't have worked.
For a while today it seemed like Corbyn might be able to use that confidence to get Cameron exactly where he wanted him. He once again led on tax credits, making the Tory benches visibly uncomfortable. Cameron strayed all over the place to assure people they would not ultimately be losing money, but it is quite clear they will. And worse, they will receive a letter before Christmas confirming exactly how much money they'll lose. Printed statements make for a uniquely compelling sense of injustice.
Cameron tried his usual trick of highlighting divisions in Labour, this time by asking why Tom Watson wasn't at the tax credits vote last night. Corbyn just ignored it. This tactic does not work against him. Unlike Ed Miliband, you can't see the inner discomfort contorting his face.
But the Labour leader once again decided to let the subject lie after three questions and moved onto something else. He still does not seem to understand the value of follow up questions. While Miliband could have used some of his manner, Corbyn could use some of his predecessor's forensic tactics. He was gradually turning the screws on the prime minister but then decided to move onto steel and disabled rights. Steel is undoubtedly a crucial matter, but it let Cameron off the hook. That's two weeks in a row the prime minister has looked relieved. The fact he does at all is a minor victory for Corbyn, but he shouldn't be making the same mistake twice.
After the exchange, PMQs again descended to its usual fare: angry tirades, red-faced anger and mean laughter. It's another measure of Corbyn's remarkable presence that the chamber stays subdued while he is standing up. But without a more canny assessment of Cameron's weaknesses and an ability to think on his feet, all that confidence will accomplish nothing.