You turned 50 recently. How did you celebrate?

I went to the cinema in the middle of the day to see the new Woody Allen film, Blue Jasmine. As a special treat, my wife and I went to the cinema to sit among an audience of unemployed men and pensioners. And there was I, somewhere in the middle. Straddling both. My 50s feel OK so far. Middle age has always been my natural age anyway.

Alan Partridge: Alpha Papa was a huge hit this year, both critically and at the box office. Was that a relief?

We genuinely didn't know what to expect so the reaction was very refreshing. There's an Alan Partridge fanbase, obviously. There's still a collective out there of Alan aficionados. Afic-alan-ados. Alan-istas. But you don't know how much of that is from 20 years ago and how much of that is a television audience rather than a potential cinema audience. There were lots of imponderables.

A pleasant surprise, then.

Very much so. We were also aware of the fate of many movies spun off TV shows. We didn't want it to be the equivalent of Holiday on the Buses, where they go to Prestatyn. We wanted to make it true to Alan. It's tempting to make it all "filmy" and go enormous and elaborate, but I refer you to Blue Jasmine. That's just a few couples yet it fills a film. It's what you do with a story and where it takes you – that's what counts.

What were some of the rejected concepts?

Some of the ideas we quite liked, but gradually we just thought no, let's rein it in. There was one where Alan ended up on a cruise liner doing the entertainment. There was another where he ended up becoming head of light entertainment in the United Arab Emirates. But in the end, we came back to Alan being at North Norfolk Digital. Something contained and intimate, then pacy at the end.

The film starts with Alan in his car, singing along to Cuddly Toy by Roachford. Why that song?

Steve [Coogan] is always good at choosing Alan's playlist. A lot of moments like that come from us procrastinating. If there's a scene we need to write and we know it's going to be hard, we end up mucking around instead. That's when stupid bits of Alan emerge. And they always end up going into the final script.

Alan's face features in the Norwich Christmas lights. That's quite an honour.

All thanks to the generosity of Norwich city council. Simon [actor Simon Greenall] turned them on as Geordie Michael. I like the way that Norwich has now embraced Alan. It was always rather wary of him. In fact, the mayor 15 years ago was very hostile. He actually said that Alan Partridge had done more damage to Norwich city centre than terrorists could.

Nice sense of proportion there.

Indeed. My argument has always been that we like Norwich. I've been to Norwich many times and have relatives there. We don't really poke fun at Norwich, it's just that Alan lives there. We originally chose Norwich as a place that isn't London and isn't trying to be. It's not a big city like Manchester that sees itself as a rival centre of excellence with lots of media jobs. Norwich is busy but it's non-media. It's just that little bit too far away as well.

The Gibbons brothers, writing duo Rob and Neil, collaborated with you on Alan's comeback. Are you passing the Alan torch on to them?

Very much so. They came on-board with Mid-Morning Matters and at that point, me and Steve thought, Oh, there is life in Alan. Rob and Neil get it instantly. They know how to write Alan. Lots of people feel they can write him, they send in scripts and so on, but it's usually exaggerated Alan. They go one louder. Whereas Rob and Neil instinctively understand that you've got to downplay it, submerge it in reality.

Veep's second series seemed to take off in the US…

Yes, it seemed to establish itself. We won two Emmys and I got a sense it was being much more talked about. In Washington DC, people are starting to refer to each other as Dans and Jonahs. One of Obama's press secretaries said recently that when he comes back from a meeting, the first thing his colleagues ask is how many Jonahs were in the room. It's gratifying on one hand but deeply worrying on the other.

The Toronto mayor story must have tickled you?

Yes, that was huge over there [and in the US]. And Rob Ford's still in the job, that's the remarkable thing. You can sort of get away with stuff over there. If you're larger than life, people like you. Whereas if you're larger than life here, people think you're a nutter and the party gets rid of you. That's what happened under Blair: he kept all the people who were like middle managers and anyone who had a bit of idiosyncrasy, such as Clare Short, Robin Cook or Mo Mowlam, got marginalised. That's what British politics is like now.

Is that the big difference between UK and US politics, do you think?

In the UK, all the parties have converged towards a very bland middle and you can't really separate them. In America, though, it's become so polarised. Candidates mark themselves out by how different they are from their opponents. In the UK, it's very much: "We're harmless, don't think of us as being like the old Tories, we're much more woolly now." And the same with Labour. "We're not strange socialists any more, don't worry, we're not going to do anything crazy." Whereas in America it's very much: "Vote for me. I am crazy."

You're filming Veep series three at the moment but are there any more films in the pipeline?

I have got another film script that I'm very keen to do. It's a much more visual comedy, all about voyeurism and the way our lives are out there for anyone to see now. The idea of someone doing a little thing and suddenly becoming an international laughing stock because it's gone viral. The script's all written and ready. That's the next one.

Aren't you writing a novel too?

I started writing one about seven years ago. I've written half of it. Everything else in the past five years has been a displacement activity. I'd like to think I'll finish it one day.

As a comedy fan, are you excited by the Monty Python reunion?

Yes, very. I think it'll be really funny. I have high hopes for it.

What did you make of the news that your friend Peter Capaldi is the new Doctor?

Very exciting. I was so thrilled. When David Tennant stepped down four years ago, I thought in the back of my mind, I wonder if they'll ask Peter?, because I could see him as Doctor Who. Then, three or four years later, they did. He's going to have a great time.

We got a brief glimpse of his eyes in the 50th anniversary special…

Yeah, I think they're still working on his look. I imagine him being quite charismatic and dramatic. And terrifying at some points. Peter can do that: he's got that air of authority but in person he's a very genial, amiable, funny guy. He's got that full range, from playful and slightly avuncular to lord of the universe.

I guess it rules him out of ever being Malcolm Tucker again.

Well, I bought The Thick of It to an end last year anyway. Me and Peter thought we'd taken Malcolm as far as we could. It's a great contrast, going from Malcolm to the Doctor.

But what if children stumble across Thick of It repeats and get upset that Doctor Who is swearing at them?

Under the government's new web restrictions, I imagine every family will have the opportunity to say no to The Thick of It being available on their internet provider.

Alan Partridge: Alpha Papa is out now on DVD and Blu-ray