Starring in a movie opposite Johnny Depp is most people’s dream job. Paul Bettany has done it three times already, and there hasn’t been a pirate in sight in any of these films. The affable British star of Gangster No1, Wimbledon and A Beautiful Mind only has praise for his “dear friend”.

“He’s been brilliant to me, both professionally and as a friend. He’s been great to my family too, he’s a really solid human being. We had already laughed our way through two movies and there weren’t even any gags in those movies! It was nice to finally do it in front of the camera,” Paul Bettany begun.

Your previous collaborations were The Tourist and Transcendence. Did this script allow for more improvisation?

Absolutely. Johnny is one of the most relaxed actors i’ve ever worked with. We can work without any ego attached to it. I would never with any other actor in the world make so many suggestions. We could be in the middle of something and he would go totally off “book” and you just have to be there to catch it and hang in there.

How rare is that in Hollywood?

It happens more in comedy. Having said that, in Gangster No1 I had a scene with Eddie Marsan where I am interrogating him, but half of that scene was just made up. We did it in one take and just continued. And I think some amazing things can happen from that process.

Mortdecai feels more like a farce, in the best possible sense. Is that a fair description?

Yeah, I think it is. It’s in the tradition of those Inspector Clouseau films and those great British Ealing comedies. Those are the sort of movies, weirdly, that Johnny grew up watching in Kentucky. I think that’s why he is such an Anglophile.

And were those the sort of films you watched growing up in Harlesden?

I watched all sorts. I remember watching so many on an old Black & White TV, and when I watch those films again I’m surprised to find them in colour!

Having been in the industry for a while now, have you ever thought about how you might approach some of your earlier roles given what you know now.

I’ve not thought about that actually. I think you sometimes have the crushing realisation that you do know how to do something and then wake up in the middle of the night and say “oh fuck. I should have done it like that”. There have been times when I’ve asked to go back and reshoot things. That has only ever worked once though.

Which scene was that?

It was in Margin Call. There is a scene where I’m crossing over a bridge with Penn Badgley in a car. It was a few days later when I realised something was missing and I begged them to let us reshoot it. It’s a big deal because you have to get permission to shoot on those bridges as well as other costs. It’s the only time i’ve been able to get someone to let me reshoot something.

As a director yourself now, on Shelter, how would you react to someone asking you for a reshoot?

I’d be really honest about it. We did go back a reshoot a scene. That was because I wasn’t happy with something that I had done. It’s a really hard thing to do when you are on a 21 day shoot. Our easiest day had 23 set-ups with a single camera. I’d have probably said we just don’t have the money to go back. I’d also look back at it and say “You’re wrong. The scene is there and i’m happy with it.”. I’d be honest about the boundaries. It might be a case of we haven’t got the money. It is an amazing experience.

Did you come off the back of a much bigger film?

Funnily enough, I left my monitor with my luggage and flew straight to Mortdecai. That was really intense. I was talking to a director friend, Darren Aronofsky and he said “Well that’s great! I get two weeks off and then have to go straight back and start editing. It’s great you can go off and do something fun.” That’s ok, unless you are a virgin at it. You just want to know if the thing cuts. Letting it be for four months and then going back into the editing room was actually a good thing. It was an anxious few months though.

Did you take anything from your previous experiences with directors?

For sure. Aside from the great actors on Shelter [including Bettany’s wife Jennifer Connelly], my directing friends were my biggest asset. I’d end up having terrifying screenings with Darren Aronofsky and Ron Howard there. David Koepp also came to a screening and gave me some great words.

Finally we can’t leave without asking about The Avengers. In the sequel out this year you play Jarvis again, as well as a new character. What can you tell us about The Vision.

The Vision is a Marvel asset. I’m so not allowed to say much more! We’ve kept it all so secret so far. I’ve known about this for three years and not said a word. They are intent on keeping it quiet until the release. It was fantastic fun though. Again, it was going from making a film where you can’t afford two cameras to this. I will say this, they were the biggest movie sets I have ever seen in my life! I’ve never worked on bigger sets. It felt like being a kid again, like the first time I walked onto a movie set. There were drone cameras flying around all over the place.

Does the scale of something like that make you want to direct something similar?

Oh wow. Right now, I don’t have any idea how to do that. I’m sure you’re surrounded by people that help you, but that is a puzzle that gets smaller and smaller and smaller until it is grains of sand. That stuff is a different type of filmmaking and a different type of working with actors.

Mortdecai is out in cinemas now.