Last June, when barely in his 40s, Markus Birdman had a stroke, losing half his eyesight through a rare condition called homonymous hemianopsia. And as a comic of 20 years’ standing, his thoughts immediately turned to how to make this life-changing incident funny.

This is the result, and job very much done. He has mined everything for humour, from the darkest moments of diagnosis to the humiliations he endured in the name of medical investigation – and hit gold.

Crucially, nothing is overplayed for drama or pathos; there’s no self-conscious ‘sad bit’ to turn to lend some emotional heft to the story. It’s quite clear his ordeal was intense and worrying, so he need not milk it further. Whenever he mentions a stressful turn of events, it’s matter-of-factly. The seriousness never lasts long before he cuts in with a joke.

And what a lot of those there are! In his preamble, some ideas might be over-familiar, such as the anti-vaxxer refusing the jab because ‘you don’t know what’s in it’ while happily devouring dubious drugs. But it establishes both his commitment to maintaining a high gag rate and his belief that joke’s a joke, wherever it may come from, as he proudly takes a bow for a convoluted pun, the audience encouraging his audacity to get away with it.

It’s part of a contract he makes with us, that everything’s up for a laugh even – or, more accurately, especially – the medical problems which mean he now performs while sitting on a bar stool. That more relaxed stance nails the ‘air of gentle authority’ he was aiming for – but his innate skills meant that was never in question.

There’s an edge to many of the punchlines, some of which – including those he ill-advisedly told at a Stroke Association event – would be considered decidedly un-PC, had he not earned the right to tell them the hard way.

He playfully quips about stroke not being the sort of fashionable condition that attracts a slew of celebrity ambassadors, and about the endless tests he underwent, including consuming a radioactive dye. And there’s more heartfelt moments when he considers his mortality and expresses thanks for the support of those around him, especially his partner. But he never lingers on these for longer than necessary. He’s an Essex bloke of little sentimentality, his story an engine for gags, not for sympathy. 

That attitude also gives him other topics to make light of, such as the British love of a drink – he initially mistook his stoke for a hangover – and a bloke’s reluctance to seek medical help, whatever’s wrong. And he adopts a mischievous forgeyish persona when considering modern mores.

The result is a torrent of formidable gags, skilfully told, and with a gripping story underpinning them all. 

• Markus Birdman: The Bearable Heaviness of Nearly Not Being is on at PBH’s Free Fringe @ Banshee Labyrinth at 5.10pm. His last show is today, as he has cancelled the last week to undergo further treatment.