Unfortunately, it all goes downhill from there.

After the efficient wordplay that opens his set, he starts to concentrate on the stutter from which he suffers. ‘Write about what you know’ is the comedian’s mantra, so it’s only to be expected that he will tackle the affliction that sets him apart.

But, from a comedy angle, there’s a very limited number of jokes you can do about stammering, and they tend to be based either on the listener guessing the end of a sentence and getting it wrong, or a situation in which not speaking quickly and clearly might be a disadvantage. The formula’s that simple.

Fair play to Campell, he does get a couple of strong gags from that premise, but it quickly becomes repetitive (ironically enough, I suppose) when a whole 20-minute set has to be sustained on the same pattern. But somehow, at the time of writing, Campbell has eked three hour-long shows from his condition.

But most frustrating, damaging even, is that he has absolutely no confidence in his own material. A good proportion of punchlines are accompanied by a hugely self-conscious laugh, sounding like he’s trying to convince himself that whatever story he’s just told is actually funny. This could be an endearing affectation, but it actually seems rather desperate.

He’s also anxious to distance himself from almost every one of his own jokes. Backpedalling furiously after each self-deprecating gag – usually revolving around his gauche incompetence when talking to women - he’s keen to explain that the story never really happened, for fear we might think less of him. But it demolishes any sort of flow or rapport that would convince the audience of his abilities.

It’s the demeanor of a rookie who hasn’t yet built up any certainty about who they are or the untested material they’re delivering – yet Campbell has been going since 2001, and ought to have conquered his shyness by now, or at least learn to work with it better than this.