Maybe it’s all down to Botox. A daily dose of a hundred tiny needles. Or perhaps, in some dusty attic back in Chipping Norton there’s a portrait that is visibly ageing by the hour. A mirror image of the Picture of Dorian Gray. Most former world leaders look like shit after six years in the job. The pressures of work ravage their face. Tony Blair looks like a hollowed-out skull. Even after three years, Boris Johnson looked like Boris Johnson. That bad. But David – make that Lord – Cameron is the remarkable exception. His complexion is still a glossy puce. Barely a wrinkle to be seen. It’s almost surreal. Nothing has got to him. The years of the failed Conservative austerity plan that he initiated and ended with the current cost of living crisis. Nothing. Untouched. As for the careless Brexit referendum that sent the UK into an unnecessary psychodrama from which it is still to recover, Lord Big Dave is as smooth as the day he turned his back and walked away from the country the day after the vote. Not even being caught lobbying for a dodgy financier has left a mark. The secret to Lord Big Dave is that nothing really ever gets to him. He operates almost entirely on a superficial level. The surface is all. And the surface is pure teflon. Nothing sticks to him. Pour any amount of crap on his head and he wipes clean in seconds. The ultimate Shiny, Happy Person. Most of us thought we had seen the end of him. To become a curiosity, much like Liz Truss, in the rogue’s gallery of former prime ministers at the Cenotaph. More fool us. Because Rishi Sunak had another plan. Having run out of any suitable candidates among the ranks of his own MPs, he summoned Dave out of retirement. “How about I make you a Lord and you do a year as foreign secretary before I lose the election?” The democratic flaw in the appointment was that Lord Big Dave would be subject to almost no scrutiny from parliament. Foreign Office questions would be a no no. As would making any statement, answering an urgent question or opening a debate. The Untouchable Dave had just become the Even More Untouchable Dave. The only accountability would be the occasional appearance before the foreign affairs select committee. Which is why, two months after he took the job, the profoundly chillaxed Lord Big Dave – flanked by his permanent secretary, Sir Philip Barton – was ushered into the Thatcher Room of Portcullis House for his first appearance before the committee. The pair were pursued by any number of teenagers. It seems that the Foreign Office is now being run by people on work experience. Presumably they all leave after a couple of years to take jobs filling shelves at Lidl. The committee chair, Alicia Kearns, was determined to make her presence felt. This was her committee and she wanted maximum air time. Think of it as an audition. For whatever she does after the next election. Panto, perhaps. “So how did you come to get the job?” she asked. It must niggle her that she was never in the frame. Lord Big Dave breathed out. How he had got all his previous jobs. Contacts. Charm. No real experience. The way you would expect a chap like him to get a job. It had been like this. He had just happened to be in Downing Street – as you do – and Rishi had said that he was planning a reshuffle. So how did he fancy becoming foreign secretary? Quite a lot, actually. It wasn’t the peerage. It was his love of public service. It’s what he lived for. Yup, that would be the Lord Big Dave we know and love. The Lord Big Dave who stuck up two fingers to the country hours after completely wrecking it. Er, OK, said Kearns. So how will you be different from your predecessor? By being marginally less dim but just as superficial. Because that’s what the country demands. Not that James Cleverly had done a bad job. More that he didn’t understand that a little more was required than clocking up the air miles and eating well with foreign politicians. And no, it wouldn’t be hard to go along with policies with which he disagreed. Because if history had taught us anything it was that Lord Big Dave never really had any strongly held principles. The secret to a clean conscience is to have no conscience at all. After that we moved on to Israel and Palestine. Here Lord Big Dave went into schmoozing overdrive. Burble, burble, burble. “All very tricky … Sustained ceasefire … Two-state solution … ” Several MPs on the committee started to get a bit restless. They had rather hoped for some kind of insight that went beyond that of a below average A-level international relations student. His Lordship looked pained. What hadn’t they understood? His whole purpose in life was to hover above the surface. To leave no trace. Bland, meaningless generalisations were his trademark. Besides, did anyone for a minute imagine that either Israel or Hamas took any notice of what he said? His role was purely performative. To act the role of foreign secretary. To make it look like the UK was a global influence. But to keep everything skin deep. The work of an entitled man with boundless self-confidence. Several times Lord Big Dave was pressed on whether it was the Foreign Office understanding that Israel had broken international humanitarian law. “B-b-but you still misunderstand me,” he said, puffing his cheeks. “My job is to know nothing. That way I can’t deliberately offend anyone.” The MPs turned to Barton, who had hitherto done nothing but nod furiously. Like one of those toy dogs you used to find in cars back in the 70s. Barton was outraged. This too did not compute. His whole purpose was also to be found intellectually wanting. To not ask the difficult questions. Labour’s Fabian Hamilton moved to Libya. What did Lord Big Dave make of the committee’s report into his ill-conceived Libyan adventure that had left the country in chaos ever since? “Bunk,” said Dave brusquely. It wasn’t ill-conceived at all. Everyone knew that after a few years every world leader got desperate for an overseas war to make them feel more important. To build a legacy. And this was his. Leaving Libya in the hands of competing warlords had always been priced in. After two hours of bland generalisations, Lord Big Dave looked hopefully towards Kearns. Could he go now? Loads of the Foreign Office apparatchiks had to get home for their tea. Else they might be late for bed. • This article was amended on 9 January 2024.The permanent under-secretary at the Foreign Office is Sir Philip Barton, not Philip Norton as an earlier version said. John Crace’s book Depraved New World (Guardian Faber, £16.99) is out now. To support the Guardian and Observer, order your copy and save 18% at guardianbookshop.com. Delivery charges may apply