You're in Hungary shooting the $150m film Hercules: The Thracian Wars with Dwayne "the Rock" Johnson. Do you enjoy doing blockbusters?
Well, it used to mean that you got terrifically well paid, but it doesn't mean that any more. Nobody gets terrifically well paid any more, except perhaps the star. But I have nothing against it. You know what you let yourself in for in these things. I can't say that I wouldn't prefer to make small films, basically because I think they are probably more interesting in terms of the material. But every now and again it's quite good to do a big one.
How's it going?
With a big film, it's absolutely impossible to say… But of course we all sit around and have a good old moan. But what does an actor do when he gets given a nice part? He moans about it.
Your new film – More Than Honey, a documentary you narrate about the threat to bees – is at the other end of the scale in terms of size. Is it a subject you feel personally engaged with?
I do now. Like a lot of people, I didn't realise the threat to bees worldwide and it had never occurred to me the importance of them. But it's something mankind should be concerned about, because it's very important for the planet. We do tend to behave so often in the most cavalier way.
The film-maker Markus Imhoof has described it as "Chaplin's Modern Times as told by bees". Does it achieve that?
It does, sort of. It's not a polemic; it's more intelligent than that. As soon as you get the wagging finger, I don't know, for some reason it turns you off. But they ain't doing that.
Are you comfortable making political and social pronouncements through your work?
It's often said about actors, "Just because you're an actor, what gives you the right to do that?" But, if you have something you believe very strongly, film is a very powerful medium. You not only can talk about it but you should talk about it. It's almost a duty if you like – there's an old-fashioned word for you.
You were in a film about the Rwandan genocide, Shooting Dogs. Was that a duty?
My good friend Michael Caton-Jones called me up and said, "I'd like you to do this film. It's a film that should be made." Anyway, you read it and think, "Oh Christmas! Why did you offer me this? Because I'm now obligated to do it. And I thought I might have fun this summer!" But you can't turn it down and then of course it becomes a passion. Passion, thank God, takes over and the whole thing changes.
You live in Norfolk now and I understand you're a keen gardener…
You make it sound frightfully boring.
Is it quite a change from your Soho days?
Well, I can still go to Soho, you know. I have a flat in London, but I don't live the same Soho life I might have at one stage, no. It's called progression, I think.
Do you still paint?
Absolutely, yes. The most difficult thing about painting is the self-discipline. When I finish a job, I give myself a few days, but then I have to discipline myself quite fiercely if I want to do some painting that's worthwhile. Otherwise, you're just doodling. It's much easier when you're just told what you have to do. It's terrific: "6am pick-up; 7.30am make-up; 8am wardrobe; 8.30 on the set. Right, OK."
You've acted in films now for 50 years. Are you proud of that?
I certainly wouldn't go as far as saying proud, but I'm absolutely amazed I've lasted that long. I knew I wanted to act from a very young age – from about nine, really – but I didn't know how to go about it. I had no idea. The world was a much bigger place then. Also you didn't have the communications we have today: now we've all got the internet, we know what's going on everywhere. We didn't then. We'd only just got used to the typewriter.
You've made a lot of films in that time – around 140. Any regrets?
I'm very much of the opinion that to work is better than not to work. There are others who'd say, "No, wait around for the right thing" – and they will finish up a purer animal than me. For example, Danny Day-Lewis will only do what he thinks is right. I couldn't wait that long between films. He's wonderful Danny, but our philosophy is different in that sense. Of course, I don't do everything by any means: I do turn lots of stuff down, because it's absolute crap. But I usually find something interesting enough to do.
It's your 50th year in the business and you are about to appear as the Doctor in the 50th anniversary of Doctor Who. Both of you have had lots of reinventions. Is there a neat link there?
I'd never thought of that, but let's use it! Oh yes, there's a huge link definitely. But I had no idea that Doctor Who had got so huge; I just thought, "Brilliant, I'll be a Doctor!" I was suddenly – what do they call it? You start "trending". This is all new to me!
Is it a relief you can talk about your role, now that the costume designer let slip to the Prince of Wales that you play a "dark Doctor"?
Of course you have to remember that the Doctors are all one person, so I'm not outside of that. I can't talk about it, but I will say I was really impressed when I did it. Both the previous doctors – Matt Smith and David Tennant – boy, are they good at it. Whoa-wee! They are so quick, and there's a huge amount of learning and no time to learn it in. All that fake scientific nonsense. Terribly difficult to learn.
Have you met the Whovians?
I've done a couple of conferences where you sit and sign autographs for people and then you have photographs taken with them and a lot of them all dressed up in alien suits or Doctor Who whatevers. I was terrified of doing it because I thought they'd all be loonies, but they are absolutely, totally charming as anything. It's great fun. I'm not saying it's the healthiest thing – I don't know whether it is or isn't – but they are very charming.