As The Thick of It returns to TV for what may be the last time, its creator, satirist Armando Iannucci, is challenged by Observer chief political commentator Andrew Rawnsley to get serious about politics…

Armando Iannucci has a confession to make. "The thing is, I don't despise them," he says. "I've always been fascinated by politics. Read up on political history. Love all the election shows. I am a political geek."

At the age of 14 or 15, he would take himself off to a public library in Glasgow to read Hansard. I remark that William Hague is the only other person who has ever been heard admitting to the nerdish compulsion to read the parliamentary record as a teenager. "Yeah," he nods, wincing slightly. "I know."

We have met for lunch in a break between final edits of the new series of The Thick of It. The hugely acclaimed comedy has achieved the rare feat of being a hit with viewers, channel controllers, critics, juries of TV awards and the targets of its superbly realised satire. It has not only influenced how viewing voters think about government, it is also a reference point for how the practitioners of politics perceive themselves. I tell him that, in the 48 hours before we meet, I have heard a Downing Street official describe a meeting at Number 10 as "like a scene from The Thick of It", and a senior aide to Ed Miliband has told me of a conversation in the Labour leader's office "so surreal it could have been scripted by Armando Iannucci".

He has always taken meticulous care to make the show feel real, so he is bound to be tickled by approving notices from his victims. He recalls meeting James Purnell, who was culture secretary at the time, at a Royal Television Society dinner. They talked about the very first episode when the cast are in the back of a car feverishly trying to concoct a policy on the hoof. Purnell said: "I've been in the back of that car."

When The Thick of It was last on screen three years ago, Labour was still in power and therefore the primary target. The latest – and, he reveals to me, probably the last – series begins by training its sights on the coalition. Peter Mannion, the world-weary, technologically inept old-school Tory played by Roger Allam, channelling a substantial helping of Ken Clarke, is now in charge at Dosac, the Department of Social Affairs and Citizenship. He is in uncomfortable tandem with a minister from "the Inbetweeners", as the Lib Dems are called. There is a natural comic dynamic from the two of them "trying to look like a public united front but secretly trying to get the credit for whichever policy". Dosac's former Labour boss, the hapless Nicola Murray, played by Rebecca Front, has become leader of the opposition by a quirk of the block vote mechanism that no one understands. The cast may have shuffled positions, but the animating spirit of the satire remains the same: the cunning plans of the political class come farcically unstuck in ways that reveal them to be clueless, hopeless and powerless.

Iannucci makes viewers wait for the return of his mesmerising monster. It is not until episode 2 that we are reintroduced to Peter Capaldi as Malcolm Tucker, the confabulation of all that is most foul about spin doctors. I wonder if his creator ever worries that his most loathsome character is also his most popular. "Yes, I do worry. I find it very worrying." He finds it especially anxiety-inducing when he meets real-life spin doctors because "they always talk about how much they like Malcolm and how they try and emulate Malcolm. And I think, have we got this wrong?" When the production went to film in Downing Street, some of the inhabitants of Number 10 came out, wanting to have their pictures taken with Capaldi/Tucker. "Obviously, we all look forward to the Malcolm moments in the same way we look forward to the Darth Vader moments in Star Wars and Satan's speeches in Paradise Lost. But isn't he meant to be a horrible cunt? Isn't that who Malcolm is? So why are all these people saying, 'Do you know the one I want to be? I want to be the horrible cunt.' Doesn't that say something about politics?"

Perhaps it does. Perhaps it also says something important and not very healthy about the impact of what he puts on our screens. I love The Thick of It, but I tell him that I am also gnawed by a worm of anxiety that there are viewers who will take it not as a satire of some of the worst dimensions of politics but a representation of the totality of politics. When the denizens of his version of Westminster can't organise a photo opportunity without collapsing into calamity, never mind execute a policy that might improve someone's life, what is he trying to say about government to voters? He responds that the show "never set out to have an agenda. It wasn't a manifesto. It was entertainment."

The principal driver has always been comedic. "We see these grand looking buildings down Whitehall. So you assume the people within them kind of know what they're doing with power. And part of the comedy is going through those doors and discovering that they don't really. Although it's a big job, it's actually little people."

The contrast between the outward pomp and the inner reality also drives the comedy of Veep, his American show screened in Britain on Sky Atlantic. Taking his satire across the Atlantic entailed some risk, I suggest, because Americans tend to idealise their democracy much more than the British. "I think you're right. The interesting thing in America is how much they respect the office even though they're contemptuous of the office-holder. A lot of people were asking, do you think America is going to be ready for this? I thought I was going to get, what brings you here, a Brit, telling us about our politics?"

As it turns out, the show is another hit. If there was any hate mail from outraged Americans "it hasn't got to me – probably goes to HBO". It's up for an Emmy and HBO has commissioned a second season. Three researchers were employed in Washington to help with the "accuracy", and he worked "very closely with the cast" to avoid scripting references or gags that wouldn't work for an American audience. After a while the actors stopped saying: "We think that's a bit English." Instead, they made "a set of noises", an idea started by Julia Louis-Dreyfus, who plays the title role. "She would say, 'We think that's a bit haw-haw-haw."'

The position of vice-president, described by one of its real-life occupants as "not worth a bucket of warm piss", has all the trappings of high office and no real power, making it the perfect subject for Iannucci. A running joke has the Veep asking her assistant: "Did the president call?" and always receiving a negative answer.

How did the lad who got his teenage kicks from Hansard turn into our most gifted TV satirist, with shows bathed in praise on both sides of the Atlantic? I wonder if it's something in his Italian DNA. Italians have more reasons than most to feel betrayed by government. After mulling on it, Iannucci says he can see how his take on politics might have been shaped by his father. Before he emigrated to Britain, Dad was a journalist in Mussolini's Italy, wrote for an anti-fascist newspaper "and then had to take to the hills and join the partisans, and as soon as the war was over he got out". He found a new home in Glasgow but he wasn't a British citizen so he couldn't vote. "I remember saying to him, 'Are you not frustrated you can't vote in the election?' He said, 'Well, the last election I remember, Mussolini got in.' So, you know: what good is your vote? Maybe it was that side."

Mum was a first-generation immigrant. She was born in Glasgow but to an entirely Italian family. "So it's all Italian blood." Yet his parents "never brought us up speaking Italian because they thought it's better to feel integrated". As a result, "you feel Scottish, but not quite. But neither do you feel completely Italian. You're always slightly standing back from it and kind of observing".

Not sure whether you are inside or out?

"Yeah," he responds. "Just, well, feeling half in and half out."

Now, though, he is most definitely in with the British establishment. He has been begonged with the Order of the British Empire, an irony I want to spend some time teasing him about. You could easily imagine an episode of The Thick of It crafted around the comedy of pinning this Whitehall bauble on a man who makes his living from ridiculing government. Why accept an OBE? "I thought it would be funny. That's why," he says, a touch defensively. Funny – how? "I just think it's hilarious." He quickly adds: "I mean, I'm not intending to use it or anything."

So the credits of the new series don't say "Armando Iannucci OBE"?

"No," he recoils. "I just think it's like… I mean either you accept awards or you don't. You know, either you put yourself forward for Baftas and whatever or you don't."

Mmm. You win a Bafta because your peer group wants to salute outstanding work. You get an OBE because an official in the Cabinet Office has put you on a list.

"Someone must have nominated me," he protests. Or maybe some civil servants thought they would have the last laugh on the great satirist by dangling a morsel from the establishment's table in front of him to see whether he would gratefully bite. Didn't that occur to him?

"To be honest, I don't care if they think that. I don't care. I just thought it'd be funny and I was looking forward to ringing my mum and telling her."

She was proud? "Very pleased, yeah."

This prompts me to the speculation that he accepted the OBE in part because of the ambivalent feelings about identity we had explored earlier. The honour was a badge of acceptance. He doesn't quarrel with this idea; indeed he eagerly embraces it as a much better explanation than the earlier ones he has offered. "Yeah," he says vigorously. "My grandfather [on his mother's side] was rounded up during the second world war and put in a camp because he was Italian. So there's that element: have we quite fitted in? Do people see us as British? So I can now say, right, OK, there you are, here's a document that proves it, so don't worry. Other than that, I see it as very nice, happy to get the recognition and then put it to one side and don't mention it again."

Where would he stop? Is he hoping for a knighthood next?

"I think that would be taking the joke too far."

A question I am keen to get my teeth into is whether the treatment given to politics on British television has gone beyond a joke. He may say he does not despise politicians, he may insist that his agenda is no more than comedic, but I want to investigate whether he feels any responsibility for the fact that so many of the British do hold politics in a deep contempt, a contempt that is often richly deserved but which can also be indiscriminate, lazy and ultimately poisonous for democracy. Iannucci describes himself as "a sort of vague, woolly liberal with a small l. Left of centre-ish." Yet the moral we are invited to draw from his work is not at all "left of centre-ish". The Thick of It tells us that politics is a profession populated only by fools and knaves. The laughs nudge the viewer to the profoundly serious conclusion that all government is crap. Does he ever worry that, whether he means to or not, his message is basically the same as that of the Tea Party and Fox TV?

"Wow," he says, taken aback. "I'm not sure it says government is crap. I think it says the people in government are crap."

Does that make any difference? Either way, isn't he guiding the audience to the reactionary or nihilistic view that government is pointless? He approaches the question sideways by explaining how his thinking has developed. The first series of The Thick of It "was very much coming in on the back of Blair and Iraq, and how did that happen?" It was driven by an idea of Blair as "someone with a domineering, centralised control over government" with "a group of bully boys, the enforcers, who would visit departments and just tell the minister this is what you say, this is your newest line to take, this is your view". In the second series, "I started feeling a little bit of sympathy for politicians. We the people put this pressure on them to be absolutely perfect, to not stumble, to have a fully thought-out, fully budgeted opinion on every topic we throw at them. Not to buy anything, not to have a salary, not to go on holiday, none of that. I actually started feeling sorry for them."

Making this latest series has led him to a more fundamental conclusion. "This time around I've kind of come at it with a feeling that the whole system just doesn't work. And it's primarily because we have a generation of politicians who have done nothing apart from politics. They do the politics degree, become a researcher, become an adviser, become an MP; they're in the cabinet by the time they're 39."

True enough. Books have been written about the rise to dominance of a professional political class. Whatever their ideological differences, David Cameron, George Osborne, Ed Miliband, Ed Balls and Nick Clegg have this in common: they have spent all, or nearly all, of their adult lives in politics. Despite their lack of experience of anything else, says Iannucci, warming to this theme, "the generation we have now running politics has felt all the more the need to interfere in minute detail in the working of every department. So it's not just about the big plans – like how many hospitals can we afford. It's what kind of books you should be reading, how to do homework. What we have are people with no experience, but trying to micro-manage."

That is a speech, I remark, which would be welcomed with loud applause by many Tories. Absolutely right, they would cry: let's have much less government, sack most of the civil service, roll back the meddlesome state. He again protests that this is not his agenda. "There's an alternative view. The machinery of government can work, but what you [the politician] need is not to feel that you are infallible. It's all right to take your time and actually listen to people with more specialist knowledge. Because the other thing that's weird is that someone could be running, say, the health service for 18 months and then overnight is in charge of the military or police or prisons – do you know what I mean?"

I do. Mind you, I have my doubts that government by "experts", also known as vested interests, would always prove to be a great experience for the voters. Is he saying that the army should answer only to generals, education policy should be made only by teachers and how we run jails should be the sole prerogative of prison officers?

"No, no, no, no, no," he responds. "But I think what's happened, as you pointed out, is as they got less and less direct power, we've built up this idea of politicians being these super beings from whom all final decisions flow, and I just feel that something's kind of not right. I don't have the solution to it. It's just an observation that I feel it doesn't work."

In portraying those who govern us as blundering idiots or amoral schemers, he splices the two strongest traditions of political satire on British television. Yes Minister and its sequel Yes, Prime Minister depicted politicians as the gulled puppets of wily civil servants. Antony Jay and Jonathan Lynn had a great success with that in the 1980s, despite their show being utterly untrue to reality. Margaret Thatcher, the least Jim Hackerish of politicians, was bending the civil service – and a whole lot else – to her will.

The politician as machinating villain inspired the antihero of Michael Dobbs's House of Cards, in which a satanic Ian Richardson as Francis Urquhart murdered his way to the premiership. Laurence Marks and Maurice Gran created the Thatcherite grotesque, Alan B'Stard for Rik Mayall.

While consistently excelling at satirising Westminster, British television has failed – in fact, rarely even attempted– to dramatise politics as it really is. The Americans had a go with The West Wing. Aaron Sorkin's show was too romantic to be entirely realistic – "a liberal wet dream" of an American presidency, as Wall Street Journal columnist Peggy Noonan described it. Its considerable merit was that it attempted to show politicians and their advisers wrestling with sophisticated policy dilemmas and hard moral choices, sometimes getting it wrong and sometimes right.

The Danish political drama, Borgen, recently shown on BBC4, is a classy, gripping and highly textured series that gives an authentic sense of the pressures of running a modern government and how the stress can destroy relationships, even between fundamentally decent people.

I ask Iannucci why he thinks British television has not been capable of producing something comparable? Part of the problem, he says, is persuading TV executives to commission anything about politics. "I remember when I was getting The Thick of It under way. It was a time when if you said 'politics' to them, they'd say, 'No, people aren't interested. Boring. Wouldn't get viewers.'"

He was fortunate: "I think I was quite lucky because BBC4 was just starting and that was seen as being a bit experimental – so we could try it. If it didn't work, it didn't work. At least we tried it. And it also meant we didn't have much money, so that affected the style of it, the very fast shooting style."

He thinks it may also have something to do with Americans having developed a different attitude towards television. "They just take it more seriously. It used to be film was the art form. I think they realise, as TV screens have got bigger, TV is like a movie experience in the home. So now you can actually do more with television, up the game and do more challenging work. We're just beginning in the UK to think we've been caught napping."

The next challenge for him is whether there is much more satirical juice to be squeezed out of our political lemons. Fiction now struggles to compete with reality when Boris Johnson makes an arse of himself by getting stuck on a zip wire, Jeremy Hunt almost clouts a bystander with an Olympic bell, the budget unravels over taxes on pasties, David Cameron texts "lol" to a tabloid executive without knowing it stands for "laugh out loud" and Francis Maude recommends that people prepare for a petrol shortage by filling up their jerry cans. I put it to Iannucci that it is time to swivel his guns on to a fresh target, to go after people who really wield great, global, unaccountable power: bankers, say, or the magnates of social media.

This suggestion is greeted with a smile: "I'm thinking that very thought."

He goes on to explain: "Probably this will be the last series of The Thick of It. The door is left open at the end to come back and do specials. But I feel I have explored every crevice now and it's time to take stock and move on. I'm thinking about the power of the internet."

This sounds like an excellent idea. Who, after all, has the more power: a British cabinet minister or the emperors of Google?

"Exactly," he nods. "Microsoft, Google, Facebook: you have these twentysomethings who have a way into billions of households. It's what we were talking about earlier: where's the power gone? The power is gravitating towards these companies."

He reveals that he has already done a script for HBO for a show set in Silicon Valley.

"I'm also interested in that personal thing of what it does to you when you're 25 and you're a multibillionaire and everyone in the world knows who you are."

I'm glad to hear this. It is long past time that the over-revered, under-scrutinised, vastly rich and powerful spiders of the web felt the business end of a sharp satirical stick. I can't think of anyone better to wield it than the brilliant geek from Glasgow.