The panel show has spawned books and apps – and become as significant a cultural export as Doctor Who. But can it survive the departure of its quizmaster of 13 years? Zoe Williams goes on set to find out

“We spend six months researching each show,” says James Harkin. “I think you can tell. I don’t know how you can tell, but you can. It feels like it shouldn’t make a difference, but somehow it does. And I think that’s the difference between QI and other panel shows that do comedy.”

Harkin is one of “the elves” (or researchers) on QI, which after 13 years on air is making the probably-scarier-than-anyone-would-admit change from Stephen Fry as presenter to Sandi Toksvig. “But then sometimes,” interjects Andrew Hunter Murray, another elf, “you see something that’s front-page news and think, ‘I’m having that.’”

I had a terrible crisis in my 40s, getting very depressed and angry. So I set out to find the meaning of life John Lloyd

John Lloyd – architect not only of QI but also of most that is worthwhile in modern British TV, from Blackadder to Spitting Image – has a near-religious reverence for facts. “I really do believe that ‘interestedness’ is the panacea for everything,” he says, weighing each word, distributing credit equally and elegantly to all of the programme’s participants, expressing himself with puckish sincerity, approaching a pizza with the doleful expression of one who knows only too well the discourteous amount of chewing it will entail.

Facebook Twitter Pinterest ‘It’s very tiring mentally’ … Alan Davies (right) with Gyles Brandreth. Photograph: Antonio Olmos for the Observer

“If everyone was as interested as the elves,” he explains boldly, “there wouldn’t be any wars. Not to be gender specific, but as a woman, I bet you’ve noticed this: men think you’re interesting if you listen.” I decide to swerve this point, because surely this makes it a socially useful thing that men like women who listen, but Lloyd’s passion is endearing – and hard won. Twenty-five years ago, he had just won two Baftas: one for Blackadder, the other a lifetime achievement award. “My wife and I were conventionally successful, I ran massive television companies, she ran a massive publisher. You don’t think you’re a martinet or a dictator, but you’re used to getting your own way.

“Then I had a terrible crisis in my early 40s, because everything began to go wrong. I started getting fired from everything. I tried to start things; they didn’t happen. I didn’t seem to be in control of my own life. I got very depressed and very angry, actually. The core questions were, ‘What’s it all about? Why are we alive? How do we get to be alive?’ I set out to find the meaning of life. I started off with physics, then philosophy. You have a completely different take on the Bible if you’ve studied Chinese philosophy. You can see what it’s getting at.”

Is it like a family? 'There’s a fair amount of nepotism. It is familial in that sense' Alan Davies

Many things were probably born from this, but one of them was QI, which began as a book idea and became a panel show. It then spawned books, spinoffs (The Museum of Curiosity radio show, the No Such Thing As a Fish podcast) and apps – an entire culture of interestedness, which in its main incarnation alone is as significant a cultural export as Doctor Who.

I guess – this will sound bad – I have managed to relish the show for all its 13 years without noticing how seriously they took the quiz element, thinking it was mainly about the surreal genius of Alan Davies and its alchemical reaction with Stephen Fry’s headmasterly omniscience, with other comedians acting as fresh meat and the answers more of a garnish. I don’t even know what makes a good fact.

Being chased by a male yeti is more frightening than being chased by a female yeti

Anne Miller and Anna Ptaszynski, more elves, try to explain. “It makes you want to go and tell someone,” Miller says. Ptaszynski adds: “So if I said, ‘The capital of Peru is Lima …’” We all nod, having established the rock-bottom comprehension that this is not an interesting fact. She continues: “But if somebody said, ‘The reason it’s called Lima is that the first person to discover it loved limes, or it was full of lemurs and it’s the result of a misspelling.” Unfortunately, I am still not interested.

“It has to be about something you’re familiar with already,” says Hunter Murray, “and then it has to tell you something unusual about that thing. If it’s about pencils, the world’s biggest pencil is in Malaysia, which is also the biggest exporter of rubber.” Now I’m panicking that I’m the kind of uninterested person who starts wars. Miller tries a different tack. “It’s very difficult to do something about facts that aren’t real, so vampire facts and yeti facts are quite difficult. But you can do it.”

Facebook Twitter Pinterest That’s showbiz … Jimmy Carr talks to accountant turned researcher James Harkin. Photograph: Antonio Olmos for the Observer

Their ideas elf, Dan Schreiber, has a favourite yeti fact, she says. “If you’re being chased by a male yeti, it’s more frightening than if you’re being chased by a female yeti, because a female yeti has such large breasts that she has to fling them over her shoulders, which gives you time to escape.” Um, a bit interesting. “And in vampire lore, a good way to protect your house is to sprinkle grains of rice around it, because vampires love to count, so they wouldn’t be able to come in until they’d counted them.” I love that fact. Perhaps we all have a varying aptitude for interestedness and these researchers – as a hand-picked super-interested elite – can coax it out. “They’re all obsessive,” Lloyd says admiringly. “They keep worrying the bone like a dog.”

I certainly witness a lot of mutual admiration on my visit to the QI set: of everyone for the elves, of the elves for the director (Ian Lorimer has directed every episode), of producers for the guests. It’s all nicknames and jokes that have lasted a decade. “It’s almost sickening how nice everybody is,” Lloyd agrees. “There’s very little grit in the shoe.”

Facebook Twitter Pinterest ‘You need to make it your own’ … Sandi Toksvig waits in the wings. Photograph: Antonio Olmos for the Observer

In fact, without Alan Davies’s wry whingeing, delivered so winningly that it cannot be reproduced on a page, the show might be a bit unbearable. “It is very tiring mentally,” says Davies. “I’m 50 now, so it’s even more tiring than it was when I was 40. And I’ve got all these babies, the house is full of babies. So all in all, I find it quite fatiguing.” But it’s the best job ever, right? Like a family? “There’s a fair amount of nepotism, quite a lot of the people who get hired are people’s friends and family members. It is familial, in that sense.”

That’s not true of all the elves, though. Harkin was working as an accountant in Salford, “finishing my work very quickly each month, and they wouldn’t give me any more, so I spent a lot of time on the internet”. He won a lot of QI competitions and was then offered a job. He didn’t want to take it because he didn’t like the sound of TV, so Lloyd offered him some accountancy on the side. But, generally, Davies is right: a lot of elf journeys start with someone’s uncle bumping into some executive at a conference. Lloyd says the programme doesn’t find people, the people find the programme.

Anyway, that’s showbiz. Back to Davies, who offered to leave when Fry left, in case Lloyd wanted a clean sweep. Predictably, Lloyd demurred. In the episode I saw being filmed, as in most I’ve seen, Davies makes the show. Toksvig, meanwhile, is a total pro, inhabiting the quizmaster role completely: idiosyncratic, gleeful, bringing the nous of years on the News Quiz but neither replicating that persona, nor trying to ape Fry’s. She says it was the only job in TV she’d ever wanted. “You have to make it your own,” she adds. “I’m not here as a mini-me for Stephen.”

Facebook Twitter Pinterest Toksvig warms up the QI audience. Photograph: Antonio Olmos for the Observer

QI is a show with a lot of moving parts: tons of facts and four comedians, not all of them hilarious all the time, some not funny at all. But there is a deftness and depth to Davies, lifting conversations out of cul-de-sacs, drawing them into whirlpools, choreographing something quite complex and daring, while insisting that he’s just clowning about.

But I continue, wilfully, to miss the point. QI is not about anyone in particular, nor is it even about the chemistry of the panel. “People sometimes say it’s like radio on television,” Lloyd says, “but that doesn’t come close to the visual richness. The pictures are delicious, and they’re meant to give you a sense of how beautiful, strange and interesting everything is. Interestingness was the core. When I discovered that, I felt like I’d discovered a new chemical element.”

• QI begins on BBC2 this autumn.