Interview: Kermode and Mayo celebrate a decade of Wittertainment

Maybe I've misjudged the situation. It's certainly enough to make me wonder aloud how they must feel about this misapprehension that they've got a fractious relationship.

"Misapprehension?" says Mark, immediately dispelling any illusions that I had.

"It's all him, he's the snappy one," says Simon. "I'm the genial host, the family favourite. It only comes about because sometimes Mark is incomprehensible. My role is to say what the audience is thinking.

"When Mark says that everyone's read Nietzsche, my impression is that very few have read Nietzsche. So I get in there on behalf of them. I'm speaking for the nation and Mark is just speaking for himself."

For his part, Mark seems happy to be on the receiving end of Simon's dry and pointed putdowns, all delivered between sips of coffee. After all, it allows him to be the more garrulous of the pair, the one famed for his passion for The Exorcist and his lambasting of some of the more execrable movies he's had to endure.

Over the years he's described The Santa Clause 3 as "the cinematic equivalent of tertiary syphilis", Little Man as being "possessed by the devil" and has compared Johnny Depp's performance in Pirates of the Caribbean to "a drunk karaoke singer showing off in a small room".

But it turns out that these breathless diatribes, which have become known by fans as "Kermodian rants", can be traced back to the earliest days of Mark's broadcasting career.

"The first time I did radio was with Sarah Ward at LBC and I had no idea what was going on. I thought that it was going to be organised and civilised and everyone would sit down in a green room and eat croissants and exchange banter and then you'd do the show.

"What I discovered was that you rang the doorbell, they showed you into the studio and you were live on air. So I just didn't stop talking and, at the end of three minutes, they said 'stop' and saw me out.

"I thought it was a catastrophe, so the next week I went back and I'd prepared and written everything out, which I thought was really sensible.

"And afterwards they said they'd much preferred it when I'd pretended I didn't know what I was doing. I realised then that live radio wasn't about reading things out like the speaking clock."

It was while working on Mark Radcliffe's Graveyard Shift at BBC Radio 1 in 1993 that he came to the attention of Simon Mayo, via the then controller Matthew Bannister.

"I was moving to mid-mornings from breakfast," recalls Simon. "I wanted to have some movie reviews on the show and he said, 'There's this weirdo who does stuff for Mark and Lard. Why don't you try him?'"

Mark, however, admits that the whole deal could have collapsed before it had really begun: "I was late for one of the first things we did together. It was a live programme and I was in a taxi that pranged another vehicle.

"And I thought, I've got this gig at Radio 1 and it's all over. I remember sitting in the taxi listening to the show and me not being on it."

But this first phase of their partnership was to last five years and was broken only by Mark leaving the station in the belief that he was "now twice as old as the average listener".

Reunited when Simon took the job presenting afternoons on 5 Live in 2001, the pair have since gone on to pick up a mantelpiece-full of Sonys for their self-styled "wittertainment".

Even when Simon shifted over to Radio 2 to take over Drivetime in 2010, the film reviews stayed on the news-and-sport station, now in an expanded two-hour slot.

"There's no other programme like it on radio or television," says Simon. "All the rest are geared around new releases. But what we recognise is that people are still talking about that new release in a month's time because that's when they've finally got around to seeing it.

"So ours is an ongoing movie conversation that's built around the box-office top ten and the new stuff, but we keep the discussion going because that's what people are doing out there."

In order to mark a decade's worth of shows, there'll be a series of special events, including a live broadcast in front of an audience at Mark's favourite cinema, the Phoenix in East Finchley.

The celebrations will culminate in a birthday extravaganza on 10 June at Media City, Salford, where the guests will be the BBC Philharmonic Orchestra, who'll be playing extracts from some of the greatest film scores of all time.

As has become the norm, the listeners have got involved by texting which piece of music they want to hear in full: either the theme from Raiders of the Lost Ark or Jaws, with Indy having recently been announced as the winner.

All of which brings us to the role played by those who tune in on a Friday or download the podcast. This is a programme that galvanises its audience in a way that's quite rare, as Simon demonstrates by showing me the thick wodge of A4 in front of him that's solely that day's correspondence.

For instance, there's a tradition of fans sending in nicknames for Hollywood actors that then get adopted by Mark, hence now-routine mentions of Orloondo Bland, Ikea Knightley and Matthew Mahogany.

Plus there's the strange case of Mark's review of Percy Jackson & the Lightning Thief - a film judged to be so derivative of Harry Potter that it could just as easily have been called "Benjamin Sniddlegrass and the Cauldron of Penguins".

This then inspired Australian film-maker and podcast listener Jeremy Dylan to make an independent feature-length movie entitled just that, complete with in-jokes about Kermode favourite Werner Herzog and, most astoundingly, a narration by Harry Potter audiobook maestro Stephen Fry.

"The Benjamin Sniddlegrass thing is a classic example of how the whole thing feeds back both ways," says Mark. "One minute I was reviewing Percy Jackson and the next thing you know, the listener writes in and asks to make the movie. And then he goes and does it.

"It's part of the ongoing conversation - although we're definitely stealing more from the audience."

What the audience gets back in return are all of Simon and Mark's long-standing grievances with each other, which now take up a hefty part of each show.

"We couldn't do the reviews in 30 or 40 minutes any more," admits Mark. "There's too much domestic stuff to get out of the way. You have to remember that our relationship exists almost entirely on air. We live in different towns."

"You live in the middle of a forest," says Simon, referring to the village of Brockenhurst in Hampshire.

"Yes and he lives in London's urban noir. I'm basically in Narnia and he's in Attack the Block."

I decide to finish by asking about some of their playful niggles, including the small matter of Simon having still not read Mark's autobiography It's Only a Movie, despite having a large role within its pages:

"I haven't seen The Exorcist either. But I get more mileage on the programme from having not seen The Exorcist. Or having not read his book. It's more fun to be deliberately obtuse because once I have read it, it'll be the end of that gag.

"So I might as well carry on. Plus I've got a book coming out and the only reason I've done it is so that Mark doesn't have to read it."

There's also Simon's exasperation with Mark interrupting the emails he's trying to read out. Is Mark now making a concerted effort to bite his tongue?

"Have you noticed any change?" Simon asks me.

I admit that I haven't.

"Look, for a start there are some things you just can't not interrupt," protests Mark, but before he has a chance to expand, Simon is the one cutting him off.

"I feel that listeners shouldn't be corrected. If Mark feels that something should be corrected, he interrupts." And then, following one final taste of coffee, he adds with a smile, "Which is why the nation loves him so much."