Comedy has its careerists: thrusting tyros zeroing in on the fame, the TV gigs, the movie roles. But there are other, more circuitous routes to the top. The fictional Count Arthur Strong certainly took one, via the dog days of vaudeville and bit parts in Hammer horrors. His creator Steve Delaney took one too, meandering from drama school to a carpentry career to the slow gestation of his alter ego, away from the circuit’s bright lights.

The Count is a star now; his sitcom – co-written with Graham Linehan – ran for three series to 2017. But he was once an oddity on the Edinburgh fringe, where I started watching him at the turn of the century – an experience never to be forgotten, for various reasons. Yes, this blithering, dyspeptic old-school entertainer was a creation of near-genius, and Delaney’s blood vessel-busting performance a spectacle to behold. But – wow! – those early shows could be gruelling. The joke was in Arthur’s frustration and confusion, as his own waning powers (of memory, movement, syntax) thwarted this or that overreaching set piece. Often, Delaney took that joke to painful, patience-fraying extremes.

Indomitabubble … Count Arthur Strong. Photograph: Des Willie/BBC/Retort

I laughed, I winced – and I watched as other audience members walked out. (“Three quarters getting it and a quarter not,” says Delaney now: “That works for me!”) I certainly didn’t peg Count Arthur as a national treasure in waiting – his BBC One sitcom twice Bafta-nominated, his radio show multi-award-winning, his national tours a fun-for-all-the-family hot ticket. “I always thought Arthur would work in a sitcom,” Delaney tells me. “I never had any question about the various things he would work in. I believe in the character.”

And so he should: it’s his life’s work. Delaney is 64 now, and – chatting at his publicist’s HQ before another UK tour – he’s looking good on it. A gentle chap with a naive air about him, he’s grown into Arthur, whom he dreamed up in the 80s. Delaney was studying at Central School of Speech and Drama, and needed an act for a circus-themed cabaret. Arthur was a sort-of strongman competing with Dracula to take bites out of a Bible. “It was very embryonic,” Delaney recalls. “He had the voice I used to lapse into anyway when I was arsing about. With this act, I was arsing about in a circus, so I just used that voice.”

And what a voice it is. Northern (Delaney’s from Leeds, the son of a foundryman and a seamstress), wheedling, malaprops a-go-go. “I didn’t get wherever I am by not knowing where I am.” “If this turns into a full bowl of cashews, it could chiropidise the whole show. With my feet!” (I could go on. I’d love to go on.) He is hair-trigger touchy – a trait Delaney claims to share. “I often overreact to innocent questions, immediately thinking it’s to do with something I haven’t done. That defence mechanism is big up north. It was prolific in my family.” It makes for great comedy. “Everyone likes that Arthur says what he thinks. Immediately. It goes through no filter.”

But beyond the cantankerousness, the Count is indomitable. “He’s a great optimist. He’s always on the lookout for the next thing. ‘We’ll get three of those, and I’ll set a market stall up.’ I love that about him,” says Delaney, “perhaps because it’s unlike me.”

And yet, it took initiative for Delaney to make a success of the Count. He was a bit-part actor in the 80s (Juliet Bravo, All Creatures Great and Small), and a joiner on the side. The jobs overlapped: he was sitcom star Geoffrey Palmer’s carpenter of choice. Not until 15 years after drama school did he revive the Count for the comedy stage – after which instant success, he quit acting immediately. “At drama college,” he says now, “I learned that I wasn’t versatile. I didn’t have the application you need to change what you do every time you do something. If I had a performance in me, it was about homing in on something in a very meticulous way.”

And that’s what Delaney did – far from well-trodden comedy paths. “I would hire venues. I’d put my own evenings on. I’d virtually print the tickets myself.” After six years, he quit carpentry too, and Arthur “became my living. I come from a generation where you have to have a job. And Arthur’s my job; that’s very much how I treat it.” Even today, he professes no interest in taking on other roles. “I’m not interested in being an actor” – unlike Steve Coogan, say, to whose Alan Partridge the Count is often compared. But really, there’s no analogy to be drawn, no other comic who’s dedicated a lifetime to just one character.

‘There are no other characters that could have come out of me’ … Steve Delaney. Photograph: David Levene/The Guardian

But why this character? “There are no others that could have come out of me,” says Delaney. “They say write about what you know. Well, when I was a kid in the 60s, a lot of stuff on TV was transitioning from the collapse of variety theatre. Light entertainment was fantastic: The Arthur Haynes Show, The Army Game, Bootsie and Snudge. And I place Arthur right on that transition period.” It’s a moment laced with melancholy; Count Arthur has a dark side. “When music hall was breathing its last gasp is when Arthur started getting into it. Beautifully mistimed. So he’s always been chasing it.”

Of course, whether Arthur really was a vaudevillian, or only ever performed in the music hall of his own mind, is moot. “[TV producer] Geoff Posner once told me I should map out everything Arthur’s ever done. His backstory, in effect. So I went home and got out my pen and notepad. And I don’t think I wrote a line.” That’s not how the character works. “It would place too many restrictions on his flights of fancy. I deliberately don’t answer those questions. Arthur goes on about how he was in The Bridge on the River Kwai: I don’t know if he was or not. Maybe he just really resents Alex Guinness.” He pauses, Arthur-like. “Or is it Alec Guinness? Even I don’t know what he’s called.”

For me, there's nothing funny in coming up with a character with dementia. I steer clear of it. He's a nutty old bloke

Delaney won’t be drawn on whether the forgetful Count is a portrait in senility rather than mere dottiness. “I steer clear of it. For me, there’s nothing funny in coming up with a character with dementia. The best way I can describe Arthur is, he’s a nutty old bloke. In the way people were allowed to be nutty when I was a kid. ‘Don’t go near him, he’s mad.’ People don’t grow old in the same way any more. Mind you,” he says, “even when he was young, Arthur was like that.”

At any rate, the character’s variety roots show in his stage work, where routine after routine (the ventriloquist’s Egyptian dummy; his lederhosen-clad Sound of Music tribute; or the silent comedy set-piece in which his stooges dress him as Sherlock Holmes) would grace the end of any pier. Then there are the moments that splice hilarity with agony – like the Count’s caterwauling rendition of Bill Withers’ Lovely Day in his last show The Sound of Mucus. Playing Arthur for two-and-a-half hours on stage – clenched, inflexible, barking – looks like a physical endurance test. Is it?

“I never feel that, no. I know it’s hard: I was dizzy at the end of Lovely Day, wobbling around. But if Arthur would be on his knees at the end of it, then I want to be on my knees as a performer. It might hurt in the moment, but not after the show. And besides,” he says, “those moments people call excruciating, I love them.”

There may be fewer of them these days – although Delaney insists he never toned down the character. “Some fans of the radio show didn’t like the TV show, and thought it was a watered-down version. But to me, they’re just different stories, different sides of Arthur – but the same approach from me.” Whatever the approach, it’s secured for Delaney an audience far wider than he expected. “When I was at the London Palladium, doing pantomime,” he tells me, “I was having a chat with Bobby Davro. And he said to me, ‘You are mainstream. You sell venues out’.” Delaney was puzzled by this then, and still is. “I like doing things on my own terms too much. I don’t regard what I do as mainstream at all.”

But what’s thrilling about Count Arthur’s success is it proves you can be both. Experimental and popular. Eccentric and mainstream. Successful, and diffident about success. In the Count’s case, that success shows no signs of waning, with new TV projects in development (on which he is sworn to secrecy), a foray into publishing (with semi-coherent thriller Codename Rattlesnake) and a new tour (Is There Anybody Out There?, about stargazing) all in the pipeline. Of the latter, Delaney tells me: “I’m itching to perform again as Arthur now. I’ve spent enough time writing as him, I need to get out there and do it. You always think, ‘I wonder if I can still do it?’ – and I know the answer to that question, of course I do. But I enjoy having to prove it.”