It says at the beginning of the film that most of it is true.

How much of the story did you have to change or embellish to bring it to the big screen?

Stephen Gyllenhaal:To begin with, I have yet to have a book give me all the dialogue.

So you have to make up all the dialogue.

Thats all not true, to begin with.

Well, some of it could be true!

But most of it, structurally, really was true.

Its more or less the way it happened.

And I just listened to him.

SG:He listened to everything I said.

JB:Well, that was my job!

You know, I wasnt Jamie Foxx doing Ray Charles…

There wasnt a specific guideline in terms of what we needed to encapsulate.

JB:Wow, its the perfect version of me!

The movie is all that everybody remembers.

I imagine its more important that the film is true to the storys political themes.

Were they what attracted you to it in the first place?

SG:Im very political.

I certainly love history and follow politics its almost like a drug.

But I think what really drew me to the movie was the process of democracy.

Right, left or centre.

And I think thats lazy.

Thats one of the key undercurrents of the film.

I think to a certain extent is has to.

When youre running, you have to be very specific and very smart.

And Ive learned a lot about how successful grassroots campaigns are run, and its a strategy.

But, then you have to jump in and do some stuff.

Its what making movies is about, you have to really become an adult, and its fun.

Its much more fun than living in fantasy.

And when it comes down, youre devastated.

And the audience will keep going with that.

But, of course, its a horrific movie to watch!

So thats what I keep looking for.

There was a guy, not very well known, who used to mix comedy and drama.

Back and forth, all the time.

And he will one day be rediscovered.

His name is William Shakespeare.

JB:[bursts out laughing]

Gentlemen, thank you for your time!

Grassrootsis out in UK cinemas now.