Do you vote?
Yes, I do.
You renounced your US citizenship in 2006, partly in protest against George W Bush. Did you vote there before that?
I haven't been in America for 43 years. It didn't seem to be my country any more. It wasn't just a protest. There was the fact that my wife would have had to sell the house to be able to afford to pay the taxes when I died.
You have no plans to go back?
No, no. Even though America has been blessed with possibly the best leader the world has got at the moment, I don't feel the need to go back and help him. He's on his own.
In all your films, you spill your imagination on to the screen in a way other directors don't.
Maybe they're just more cautious and career-oriented. I just do what I do. Things take me over, then I want to get them out of my system. My films are exorcisms, auto-exorcisms!
Your new film, The Imaginarium of Doctor Parnassus, is also about imagination, isn't it?
I find it hard to describe my films. That's why I always find it difficult to raise money, because I can't give a tidy little explanation. Yeah, it's about encouraging imagination in those who watch it. I hope they come out saying, "More things are possible." I think that, if anything, is what I'm trying to do -- not just get my imagination on the screen, but to try to encourage other people to develop their own. And that's one of the problems of having an imagination: trying to communicate it and keep people interested.
There's a political element to that -- the idea that another world is possible.
It's that kind of social statement that's really political. I grew up in the 1950s, with the threat of communism and the bomb. The 1960s opened it up, and now we're back in a very closed state with fear outside the gates.
So do you think human history swings between fear and optimism?
Roger Miller sang, "England swings like a pendulum do". He's a great singer in America! I don't know -- it's either a pendulum or, in the east, it's a circle. What it isn't, though, is linear.
You talked about the east there. There's a kind of metaphysics implied in the film. Passing through the imagination is like passing through the veil of illusion into something like the Buddhist realm of truth or a Platonic realm of eternal forms.
I don't subscribe to any particular religious belief any more, but I tend to believe that, to break through Maya -- the veil of illusion -- you see it. That's very much what I believe. And then there's enlightenment. When in the film those women come back from the Imaginarium, they've been enlightened - that, or that they've just been fucked! But there's been an orgasmic moment. The creative moment is orgasmic, whether it's enlightenment or sexual energy. I didn't realise it -- good Presbyterian kid, going to college on a scholarship -- but over the years, little by little, I've drifted more eastern because I just find their view of the world more enlightened, more interesting and more open. Polytheism is so much more interesting than monotheism. Monotheism is all about control. Polytheism is: "Oh there's that, there's that over there." It actually seems to be amazed at the world.
Do you see films primarily as a visual medium or as a narrative medium?
I try to make narrative films, but the narrative is only part of the tale. The problem is trying to link together a lot of different ideas -- some are visual, some are musical, some are aural . . . It's kind of a battle of all these elements.
You also art-direct your own films, don't you?
I have to, because you've got to create the world. This is just a cheap version of being God. And you've got to do it in six days. It's never enough time, just like there wasn't for him.
What about technology? Have technological developments in cinema - CGI, for example -- liberated you as a film-maker?
It hasn't liberated me, it's just made things easier. That's all it's about. You can do the same thing with people with two pieces of paper, but there's a certain visceral quality. What I really like about CG work is what the camera can do. Because we used to do the static frame, and we'd do maps, and so it was very clunk, clunk, clunk. But now I can swing the camera all over the place in front of a blue screen and the computer can track what the camera does, and then when we see the CG background or a model background the camera can replicate that move. I couldn't do that before, and that, to me, is the greatest advancement that computers have done for me.
What are the continuities between your early work for Monty Python and your film-making?
I look back at my old cartoons and the stuff is all there. I just get better at some things and worse at others. I never reach any great heights.
Did The Imaginarium come to feel like a monument to Heath Ledger, after he died?
We were just trying to make something worthy of being his last movie, and I think, in the end, we did it. In a sense, it's a monument to how much he was loved and admired. We just saw the tip of the iceberg of what he was capable of. Everyone was willing to do whatever it took to finish that film. For Johnny [Depp], Colin [Farrell] and Jude [Law] to come to the rescue -- that's never happened. Heath's last film was something that will never happen again in the history of motion pictures.
How did it come about, getting those three in the film?
That was the very difficult part of it. The first person I told when Heath died was Johnny. I was commiserating with him 'cause he was a friend of Johnny's as well, and I said, "We have to pull the plug on this whole thing," and he said, "Well, whatever you do, I'm there, I'll help you." And that was a kind of turning point. Johnny was really serious. Everyone was involved in other projects, and trying to juggle their schedules was a complete nightmare. In the end, thanks to Michael Mann's film being delayed by one week at the very last moment, Johnny popped in.
How do you think Heath Ledger will be remembered?
We just saw the tip of the iceberg -- we saw so little of what he was capable of. He was just an extraordinary actor. He was fearless; whatever he did, there was a reality and gravitas about it. It's hard to know. He was nipped in the bud. I'm glad that Parnassus is getting released because I think what Heath is doing in Parnassus is a bit more of who he was as a person.
In what sense?
He was playful, he was charming, he'd do anything. He was just so generous. The character himself is very chameleon-like; his voice is changeable. He's Aussie one minute, cockney the next -- he's everywhere. That was what Heath was capable of and a million times more. As an actor, he could shape-shift, and that's what I love about all actors. I can't do that, and they fascinate me and convince me that what they're doing is real.
Did Dickens and Hogarth inspire the film's vision of London?
They did subconsciously, because those images of London still entrance me. I remember when I first came here, I used to love walking around Shad Thames, which now is a very prosperous place; but then that part of London was so amazing and so derelict. I was seeing Chuck Dickens everywhere.
Do you think London has changed for the better or worse in those 40 years?
I find it a lot worse. It may have been my youthful romanticism, but I felt there was a greater sense of community then. When I got here in the Sixties, it was a costume party. Then you got strikes and socialism - everything seemed to be changing. And now, I don't know what it is; it's a kind of amorphous society. I think I preferred the world of three or four television channels. Now it's so diffuse. I miss that sense of society. Margaret Thatcher got rid of it very successfully.
Was there a plan?
The only plan was a negative plan. When I quit my last proper job, doing the night shift on the assembly line at the Chevrolet plant, I said I'd never work for money again and I would only do things I had control over. That was pretty much the end of my career. It closed all the easy roads that would have been more lucrative.
What would you like to forget?
I don't have a problem with that: my memory is just gone. The one thing I don't forget is the name of the problem I have, which is "nominal aphasia" - I can't remember people's names.
Are we doomed?
Oh, yes. As human beings we're built to be doomed; we can't seem to stop ourselves. But we also have resilience and we love rebuilding. We have to reach the highest part of the cliff and fall off, and then start again.
1940 Born in Medicine Lake, Minnesota
1958 BA (politics), Occidental College, LA
1967 Moves to England
1969 Starts animating Monty Python's Flying Circus
1975 Directs first film, Monty Python and the Holy Grail
1986 Brazil receives Oscar nominations for Best Screenplay and Best Art Direction
2006 Renounces US citizenship
2009 Receives Bafta Fellowship award
Interview by Jonathan Derbyshire “The Imaginarium of Doctor Parnassus" (12A) is out on 16 October.