Billy Connolly, HMV Apollo Hammersmith, London

He is, of course, a national treasure – the man voted number one by the British public for 2007's 100 Greatest Stand Ups and without whom, to quote Time Out on this 20-night near-sell-out run at London's Hammersmith Apollo, "modern comedy would look very different indeed".

Indeed. At 67 years old and in his fifth decade as a comedian and entertainer, Billy Connolly has earned the right to do just as he pleases – and tonight it quickly becomes apparent that that is exactly what he is going to do.

He starts – with an ironic aside about how revolutionary this is – by thanking everyone for coming out on such a "shitty night" and then flattering us by telling us how varied and uncategorisable a Billy Connolly audience is. Which is strange, because the auditorium seems to be filled mostly with middle-aged couples in fleecy clothes who look as comfortable sitting here as they would be at home watching Top Gear on the telly.

Instead, over the next two hours-plus, they will be entertained by a relentless stream of apparently off-the-cuff invective featuring digressions within digressions, anecdotes that trail away and either return or don't, depending on whether Connolly remembers them, a few moments of doubling up at his own brilliance and the obligatory swearathon. The audience laps up every moment and laughs its collective arse off.

I laugh once. And that's at the punchline to a joke told to Connolly by Jimmy Nail, one of several celebby names he drops loudly over the course of the evening. When he's not telling other people's jokes, Connolly's shtick these days is made up of either spittle-flecked ranting (politicians, bankers, Christians, TV chefs, Alan Titchmarsh) to which the punchline is either "fuck you", "fucker" or "fuck off", or cringey stories about, say, how annoying life is when the butler in your hotel penthouse suite won't leave you alone. (This particular tale, by far the longest uninterrupted section of the evening, ends in the "hilarious" observation that Vegemite, when smeared on to a bedsheet, looks a lot like poo.)

As all around greet each expletive as if it will be their last (it won't be), I conclude that it is he who has the problem. Am I the only one who feels as if he's listening to a psychotic cabbie putting the world to rights? Perhaps you have to agree with Connolly's opinions. Nope, can't be that. Mostly I do. What is it, then?

Perhaps it is this: that to enjoy a Billy Connolly show you have to find Connolly, if not as charming and likeable as he used to be, then at least the sort of bloke you'd still be happy to spend the night drinking with (and yes, his observational stuff about drunks is as accurate and appreciated now as when he started doing it all those years ago). But there is a thin line between spontaneous comic genius and shambolic and disconnected spite and, even if I were one of those who would like nothing more than to sink a pint with the Big Yin, Connolly would not be seen dead drinking with me. And not just because he's teetotal these days. His attitude to reviewers, as he tells the audience, is "'Funny ... Not funny ...' Who gives a fuck what you think, Cedric?".

So, for any other isolated souls out there similarly perplexed by the enduring popularity of Top Gear, sliced bread and Billy Connolly, here's another worthless verdict on our greatest-ever stand-up comedian, which, thankfully, he couldn't give a flying one about. My name's not Cedric. And you're not that funny any more.

Continues to 31 Jan (0844 844 4748)