In Cameron's final PMQs, Jeremy Corbyn proved that he will always refuse to play by the rules

After six years at 10 Downing Street, he took his leave of the House of Commons, ruefully commenting that he was the future once

David Cameron told the story, with an impressive American accent, of how when he was walking through New York with Michael Bloomberg, people came up to greet the city’s mayor, but they had no idea who he was. Until one young man pointed to him and said: “Cameron! Prime Minister’s Questions. We love your show!”

Today was Cameron’s show, and he demonstrated the “mastery” of the despatch box for which Peter Lilley, a Conservative former cabinet minister, praised him.

His exchanges with Labour leader Jeremy Corbyn were a mixture of businesslike and valedictory. Corbyn started rather gracelessly by finding only two things from the Prime Minister’s record for which to congratulate him. One was the release of Shaker Aamer, a British resident, from Guantanamo Bay, and the other was gay marriage, but Corbyn could not even give Cameron the full credit for that, pointing out that the measure was carried only with Labour votes.

Corbyn then asked a question about homelessness and Cameron said it wasn’t as bad as it had been under the Labour government.

Corbyn doesn’t play politics by the accepted rules. It is his greatest strength in the Labour Party, but it is also a weakness when it comes to winning over the wider electorate. He asked questions about workers being exploited by unscrupulous bosses, about zero-hours contracts and umbrella companies. Cameron defended his record on jobs and replied that he admired Corbyn’s tenacity, comparing him to Monty Python’s black knight (whose response to being dismembered was: “It’s just a flesh wound!”).

Corbyn read out an email from Nina, an EU citizen for 30 years, who was worried about being deported after Brexit. As he spoke, we in the press gallery watched power being handed over, as Theresa May, sitting next to Cameron, briefed him on the answer. Nina has nothing to fear, Cameron said.

At last, Corbyn softened and used his final question to thank Cameron’s mum for “her advice on ties and suits and songs”.

Because it was not his natural mode, it was all the more effective. And Corbyn was then made to look even better when Angus Robertson, the leader of the Scottish National Party MPs, managed effortlessly to outdo him in misjudging the tone of the moment. Robertson said his party would not thank him for Brexit, or for deporting the Brain family, or for renewing Trident in the vote scheduled for next week. Cameron replied mildly that he hoped the Brains would be allowed to stay.

The last question came from Kenneth Clarke, which allowed Cameron to recall how Clarke’s “first act as Chancellor of the Exchequer was to fire me as his special adviser”, and to tell the story of how his Government had tried to get Clarke as Justice Secretary to carry a mobile phone. Clarke agreed briefly, but gave it up again “because people keep ringing me on it”.

Then it was farewell. Cameron thanked his wife and children, watching from the public gallery. Florence, aged five, waved to him. He paid tribute to the House, said he would be “willing you on”, and ended by ruefully adapting his attack on Tony Blair: “I was the future once.”

The Conservative side of the Commons rose instantly to give him a standing ovation. Cameron once led his party in opposition to join the standing ovation for Blair, but Corbyn remained sitting while he clapped politely. Rosie Winterton, Labour’s semi-detached chief whip, also sat, but clapped enthusiastically to the end. The Democratic Unionist MPs on the opposition side were on their feet. Then some of the Labour backbenchers stood, led by Kate Hoey, the Brexiteer, including Ann Clwyd, Stephen Pound and David Lammy. After an awkward delay, the Liberal Democrats stood, despite Tim Farron’s obvious disappointment that the Speaker had not called him to ask a question.

And then Cameron was gone, and I saw several Conservative MPs who hope for high office under his successor follow him out, lost in their own thoughts.