'Imagine trying to do your job with Alan Partridge glaring at you': Tim Key on being Alpha Papa's Sidekick Simon

Appearing alongside Steve Coogan's Alan Partridge in new film, Alpha Papa, was a near religious experience for comedian and long-time fan Tim Key

Tim Key and Steve Coogan in Alan Partridge:Alpha Papa

I'm in the Alan Partridge movie, Alpha Papa. I play Sidekick Simon, an unspectacular man in his thirties. I also write a weekly column in The Independent's Saturday magazine. So really it was only a matter of time before someone, somewhere in The Independent's open-plan offices put together a proposal for me to write a piece about my experiences of working with Alan Partridge. I barely hesitated before negotiating the fee upwards and taking the job.

From the outset, working on Alpha Papa was a surreal and challenging experience. I remember walking into the read-through in January and almost dropping my Americano. And I am not a coffee dropper. Generally, I am unrattleable. A wasp once flew up my blouse at a wedding and, rather than squawk, I just let it sting me, again and again, as I bowed my head and listened to the readings. But an Alan Partridge read-through is a test of any man's composure. Everywhere I looked there was Lynn. And if it wasn't Lynn, it was Michael. And if it wasn't Michael, it was Dave Clifton. Icons everywhere. At these points you just have to squeeze your cup, bite your lip, and sit down next to Alan Partridge. You have been cast in the movie Alpha Papa. Just get on with it.

I am a 36-year-old Alan Partridge fan. I started consuming shortly after the man-child's conception and have watched him flourish throughout his difficult middle ages. Every incarnation has been sublime. I'm Alan Partridge was the perfect sitcom, The Day Today was a full-on mind-exploder, Partridge at its centre, twiddling his Soccermeter and shouting “Goal!”. Partridge on the telly. Partridge on video. Partridge on cassettes. Cassettes in the car. Everywhere... Partridge. I remember one hot summer, driving from barbecue to barbecue in my Ford Fiesta, me behind the wheel, Greens navigating, Partridge interviewing racing drivers, hostages, minor royals and hippies. It was heaven sent. An obsession. So much time was devoted to quoting Partridge in those years that I don't think I had a single conversation between 1992 and 1998. There was no time.

And now, amazingly, I am an insider. Cast as Sidekick Simon, I get to don comedy shirts, festooned with ganja or witty slogans, and sit in small, sound-proofed rooms with Alan Partridge. Occasionally, I am asked to deliver a line or knock out a facial expression, and then they feed me, scour off my make-up, and I leave, pinching myself. If someone had tapped on the window of the Ford Fiesta all those years ago and offered up this scenario I would have ordered Greens to spray the offending madman with anti-freeze. It is almost incomputable. But you get the gig and you do your best. I studied the scripts. I spent six months in Norwich, acclimatising. I listened to witless sidekicks on the radio. I engaged a personal trainer. Ultimately, my character is a man out of his depth, trying hard to impress Alan Partridge. Fearful of fucking everything up. In that respect, it wasn't a huge stretch.

The world of Alan Partridge has developed in conjunction with our own for the last 25 years. When you get plonked in the middle of it, it's interesting to muse on why it's been so successful, why it keeps on bouncing back, bigger, better, and more tragic. Passionate producers, smart directing and a lion-hearted crew all help, of course. And the central performance is obviously helpful.

Steve Coogan has done it for years and knows what he's doing. He infests Alan Partridge so deeply that I sometimes worry he's not going to be able to get back out at the end of a take. That he will be lost inside his creation. If they do ever go in a different direction and recast Alan Partridge, I think the current actor will be a tough act to follow. However, for me, in terms of chronicling this man's descent across two centuries, making it all simultaneously so absurd and yet so deliciously real, you have to take your Alan Partridge baseball cap off to the writers.

The writing takes the form of a complex web. Alan Partridge (and the actor who channels him) is obviously at its apex. His are the lips with which the monster speaks, and he knows better than anyone what Alan Partridge can and can't say. When to reference Bill Oddie, when to tip over into incoherence, when to stop mid-sentence and recollect a bleak moment at a Little Chef. Alan Partridge is the fulcrum. Next to him there are the Gibbons Brothers. These are the unsung heroes of the process. Pushed, pulled, whipped and kept in two large tins, these brothers are charged with keeping the beating heart of the Partridge burning by writing things for him to say for weeks, months, years, decades, as long as they're told to. They are unassuming and patient, waddling around with their Uniballs, invoking Partridge, typing it up.

And then there is Armando Iannucci. Also lending his refrigerator-sized brain to projects in the US of A, Stateside, Iannucci was there primarily in spirit during shooting – and through the Internet and texts. Though often unseen, the air was constantly thick with him. If, in this world, Alan Partridge is Jesus (and there's no question of that), then Armando Iannucci is God. And whenever there was chaos or grief on set, a giant bat sign would be shone into the night sky and Armando Iannucci would appear, becloaked, sipping root beer, and speaking in a transatlantic drawl, and he would speak unto the other members of the creative core, and he would calmly improve matters with delicious turns-of-phrase or wise finesses to storyline or character. That's it, yes. Armando Iannucci is a cross between God and Batman. But shorter, and with a more impressive CV. And he hammered it into shape in the edit.

Jesus/Alan Partridge/Coogan wears the trousers on set, of course. And my role placed me uncomfortably close to him. Horrible phrase, but I could almost taste the Toblerone. I see limitations in my performance in this film, of course I do, we all do. But I think I can excuse them. All I would say to you is this: imagine trying to do your job, but with Alan Partridge glaring at you. I don't care if you're a baker, an innards surgeon or a man in charge of a car park, if you're trying to get the job done, while at the same time contending with Alan Partridge's sad eyes boring into you, you're going to make mistakes. I still have flashbacks.

I don't have a massive part in Alpha Papa. Sure, I play Alan Partridge's sidekick but I wouldn't call it a two-hander, per se. But I feel blessed that I was chosen, that it was my blood coarsing through Sidekick Simon's veins rather than some other Alan Partridge obsessive's. Being strapped to a swivel chair with gaffer tape is never the most dignified way to earn money. But if I was going to be strapped to a swivel chair anywhere, better to be strapped to one in the epicentre of Alan Partridge's world than, say, in a windowless warehouse or a different film. Better to be swiveling there, right in the thick of it. Watching this monster craftsman close-up. Bearing witness to his senile genius. Yes, it was a very good place to be strapped to a swivel chair. It was nice to be involved.

Knowing him: the life and times of Alan Partridge, by James Mottram

Even as far back as the first series of 'I'm Alan Partridge', Steve Coogan's genius comic creation knew he needed to change with the times. Norwich's favourite broadcaster may be stuck in his ways, with music tastes that encompass “all the Britpop bands, from UB40 to Def Leppard”, but, as he tells Tony Hayers – the BBC head of programmes played by David Schneider – after reading his article on 'evolution, not revolution' in television: “That's me! I evolve. I don't revolve.”

True to form, after 22 years, with appearances on radio, television, stage, web and in print, Coogan's wonderfully inappropriate character has done just that. “You have to move the goalposts, change the arena,” reasons the actor, “so you're judged in a different environment.” Surviving the departure of early writers like playwright Patrick Marber, Partridge has gone on to become one of Britain's longest-running comedy creations.

This month sees the release of 'Alan Partridge: Alpha Papa', the highly anticipated debut movie – directed by Declan Lowney – with Alan stuck in the middle of a siege at his radio station, North Norfolk Digital, when a fellow DJ (Colm Meaney) unravels. If bringing a television character to the big screen is fraught with danger, co-writer Neil Gibbons says there was always “confidence” that it could be done. “If we'd taken someone like Basil Fawlty, who is so woven into one particular set, then that would've been more of a challenge,” he says. “But Alan does feel a lot more adaptable.”

Partridge was created in 1991 for Radio 4's newsy satire 'On The Hour', when co-creator Armando Iannucci asked Coogan to come up with a generic sports presenter – a role he'd replay on BBC2's 'The Day Today'. Within a year, Alan had his own spoof radio chat show, 'Knowing Me, Knowing You', which quickly transferred to television. It was followed by 1997's Bafta-winning sitcom 'I'm Alan Partridge', with Alan fired from the BBC, living in a travel tavern and, as Iannucci puts it, “at a really pathetic precipice emotionally”. Five years later came a second series, with Alan recovering from a breakdown. Critics were down on the series, with Iannucci admitting “we were probably guilty of over-thinking it” and Coogan developing a love-hate affair with a character that dwarfed his other work.

With the arrival of Gibbons and twin-brother Rob came a fresh outlook, with Coogan reviving the character for his 2009 live show 'Alan Partridge and Other Less Successful Characters' then for the 'Mid Morning Matters' webisodes, with Alan now at North Norfolk Digital. With the recent autobiography, 'I, Partridge', two Sky specials and the movie, the Alan of old, with his 'A-ha' catchphrase, has moved on. “Steve won't let stuff like that happen,” says director Lowney. “He really is so cautious about anything becoming overly sentimental or self-referential.”

“We've gone from minimal to the most extensive expression of Partridge yet,” says Coogan.

'Alan Partridge: Alpha Papa' is released nationwide on 7 August

This article appears in tomorrow's print edition of The Independent's Radar magazine