The man at our table was a beggar, and he was asking Alistair Darling for change

Chancellors may be handy with big money – but they’re not quite as good at finding a quid for a beggar.

I do a 15-minute programme on BBC Radio 4 called David Baddiel Tries to Understand, in which I try to understand things that I feel most people, including myself, don’t. I don’t feel it, actually: I know it, as the non-understood subjects are suggested to me by people on Twitter.

Halfway through the last series, one of my followers asked me to explain “the International Monetary Fund and global macroeconomics”. In 15 minutes. So I thought I’d give it a go.

My process, on the road to enlightenment about these subjects, involves going to speak to the experts. For this particular programme, we managed to bag the former chancellor of the Exchequer under the last Labour government, Alistair Darling. Which was very exciting.

I met Alistair at a trendy-ish café in Holborn. He did a good job of explaining to me the intricacies of modern capitalism, and, as a bonus, told me how close Britain came, in 2008, to complete financial apocalypse.

“The major banks,” he said, with a hint of well-deserved pride, “were within three hours of actually running out of money, when I wrote them a cheque for £500bn.”

Alistair had just finished rolling his tongue around this ginormous sum, basking in his saviour moment, when I noticed that a man had appeared, standing in between the former chancellor’s chair and mine. I saw straight away that this man was not a waiter (unless the café’s shabby-chic aesthetic extended ironically to the staff – which it didn’t). He was a beggar.

Almost as if God, whom I don’t believe in, had decided to become a comedy director, the beggar said, to Alistair: “Do you have any spare change?”

And, almost as if God, whom I don’t believe in, was good at this new job, Alistair searched in his pockets for a minute, and then looked up and said, in his deep Scottish brogue: “No.”

I have no idea if the beggar had overheard the ex-chancellor’s words immediately before he appeared. I don’t know if he was aware of the deeper irony of a politician telling me how his actions had saved the British economy, only for an objective correlative of how that safety net hadn’t quite caught everybody in the country to appear at his side like a karmic vision.

What I do know is that, after a short pause, as it became clear that the beggar wasn’t going away, I rooted through my pockets and gave him a quid.

Off he trotted to the next table. And the former chancellor of the Exchequer continued – with a tiny flicker in his eyes acknowledging the comic poetry of the moment – to explain to me how capitalism works.

David Baddiel performs My Family; Not the Sitcom at London’s Vaudeville Theatre from 12th September to 15th October. Davidbaddiel.com