It’s early evening on a balmy summer’s day, somewhere in rural America, when you pop round to the large but understated home of that nice old couple you’ve seen around town, just to attend to some neighbourly business. The wife is away, so the man of the house, although shabbily dressed, invites you in, pours you a long drink ad suggests you take a seat on the porch, whereupon he starts regaling you with stories of his family with a warm wit and the wisdom of his years.

In such an amiable ambiance, he starts opening up, getting a few things off his chest about his long relationship with his wife – always with affection, but happy for an audience for these minor but longstanding irritants, for once away from his wife’s ever-present gaze. As the orange sun sets over the dusty horizon, you realise his convivial company and modest indiscretions have had you transfixed for too long. You should have been home hours ago.

And that is pretty much exactly what a Bill Cosby gig feels like. At 72, he talks slowly yet effortlessly for two-and-a-quarter hours without a break, and with almost exclusively different material from his last visit here, three years ago. He mesmerises every one of the 3,000 people in the audience into feeling as if he is talking intimately to them, and in keeping with the unshowy ambiance, he’s wearing a cheap sweatshirt, baggy trousers and comfortable house shoes. Again, not millionaire entertainer, but avuncular acquaintance.

He speaks of his age, of course, of the medical procedures he now undergoes with a resigned patience, of the weary acceptance that after 45 years of marriage he’s long accepted that his wife calls the shots, or of his grandchildren, whom he clearly holds in tender affection. Yet from such modest, homespun scenarios, Cosby creates such rich, warm comedy, giving a genuine flavour of the mundane realities of aging that will hit us all, that it’s hard to convey with justice in print.

The laughs come from the timing, the nuanced emphasis on crucial words, the mastery of silence and tension, the rolling of the eyes or the pitiful hangdog expression that decades of meek compliance have etched on to his face. Aptly enough, given his career, his stand-up resembles a sitcom in a very specific way: in that it’s all about the small victories.

He still relives one such incident, involving hotel room service, 38 years after the event; the memory of that one moment still bringing a satisfied smile to an old man’s face. He raises his fist in triumph at this, and other fleeting moments, where he manages to cling onto his pride and dignity. But mostly he’s the loser, as in the incident in which he was despatched to cut down a Christmas tree which he regales with perfect deadpan, scrambling to the floor to recreate the key moments of his utter humiliation. For the most part, though, he delivers his show from the comfort of his chair, leaning forward at key moments to share a confidence or occasionally taking a stroll for emphasis.

Now and again, material might seem familiar: women’s perfect recall for arguments or what to do in case of animal attack, for example, but he’s been telling such tales with perfect charm and wit since before most modern comic’s parents were even born. And yes, the show is too long, even though it doesn’t seem to concern him. Forty-five minutes after we file out, he starts it all again, before jetting back to his Pennsylvania home.

Seeing a comedy legend first-hand can be fraught with disappointment, an expectation that can only be heightened by the trail of less-than hilarious TV shows and films Cosby has behind him. But in the flesh, he proves the incomparable mettle that made him so famous in the first place: a master storyteller with understated but brilliant wit and irresistible stage presence. His advancing years add to the gravitas, like a village elder imparting his wisdom, but that combines with an exquisite delivery undimmed by age for an inspiring performance. What a star.