During his lifetime, J. Edgar Hoover (Leonardo DiCaprio) would rise to be the most powerful man in America. As head of the Federal Bureau of Investigation for nearly 50 years, he would stop at nothing to protect his country. Through 8 presidents and 3 wars, Hoover waged battle against threats both real and perceived, often bending the rules to keep his countrymen safe. Hoover was a man who placed great value on secrets – particularly those of others – and was not afraid to use that information to exert authority over the leading figures in the nation.

Understanding that knowledge is power and fear poses opportunity, he used both to gain unprecedented influence and to build a reputation that was both formidable and untouchable. He was as guarded in his private life as he was in his public one, allowing only a small and protective inner circle into his confidence. His closest colleague, Clyde Tolson (Armie Hammer), was also his constant companion. His secretary, Helen Gandy (Naomie Watts), who was perhaps most privy to Hoover’s designs, remained loyal to the end…and beyond. As seen through the eyes of Hoover himself, ‘J. Edgar’ explores the personal and public life and relationships of a man who could distort the truth as easily as he upheld it during a life devoted to his own idea of justice, often swayed by the darker side of power. Directed by Clint Eastwood, ‘J. Edgar’ also stars Judi Dench, Josh Lucas and Ken Howard. The film is released in cinemas January 20th in the UK.

What was the biggest challenge for you taking on this biopic, especially as it’s someone who’s as prominent and contentious as J. Edgar Hoover?

Clint Eastwood: Biopics bring their own set of problems, as far as how much you want to imitate or emulate the characters? But Hoover was a very important character, a controversial character, so with that it’s important to get it somewhat accurate. The actors all pretty much studied and read every biographical book or took in any piece of material they could find once they got the roles. I think they all enjoyed that, I think they enjoyed diving in on it.

How much research did you have to do personally?

Clint Eastwood: I had a really good script from Dustin Lance Black, so I really just had a look back over the material he took it from and had to make sure there wasn’t anything missing. And for instance, there was a speech by Nixon, who does a eulogy to Hoover, and with that Dustin had paraphrased it a little bit. But when we got to doing it, we had a film clip of the actual eulogy by Nixon, so I just put that one up and told the actor, “Do that one.” You have to vamp as you constantly take in information on the characters. Listening to congressional interrogations on Helen Gandy after they wanted to know what happened to all the files, there was a big curiosity about that. And she just said that she boiled them (laughs), she shredded them all up. There was a lot of interesting things we learnt.

It seems that Helen Gandy was a devotee to service and sacrifice. Is that the backstory you gave to her? Did you see your character as sacrificing her life?

Naomi Watts: Yes, I did. Unlike Hoover’s character, there was very little information about Helen available. All we really knew was that she worked for him for 50 years. She was not married and she devoted her life to her job, the rest sort of had to be filled in. These were questions of mine in that when I read the script for the first time, I was like, “Why did she do that?” This was not common for women of that time, to go into her career saying, “This is all I want,” so she was ahead of her time. That’s an inspiration for all women to see, a woman thinking and moving differently from those around her. I liked that it was set up, in a way, that perhaps she was going to be a love interest but it just wasn’t who Hoover was despite wanting to please his mother. In terms of Helen Gandy, she wanted that career and she just went after it. She loved serving her country and making those sacrifices and she had unbelievable loyalty, and that’s what I love about the tone of the whole film. It’s a big subject in the film, the loyalty.

How did you research her?

Naomi Watts: A lot was there in the script, but they sent me this great package, massive package of endless DVD’s, a lot of documentaries, a lot of stuff on the FBI, a lot of stuff on J. Edgar Hoover himself. I used a lot of books, the internet, a lot of stuff on Youtube….I was always trying to find more information about Helen Gandy but the very nature of her job was to be in the background of this mans life. There was a couple of photographs, not much at all. It was about piecing it all together. I did manage to find the transcript of her testimony in the Library of Congress through a friend that works in government – that was actually one of the most telling pieces of information that I found, because it just reiterated what was already in the script; her level of commitment, her absolute need to service her country, her sense of duty, and even way after he passed away and her career was finished she still kept her word.

What was it about Leonardo DiCaprio that made you think that this is the guy to play J. Edgar Hoover?

Clint Eastwood: I’d watched his career advance, playing a lot of different kinds of roles. He desperately wanted to do this, he had a great instinct for it. So I think anybody who wants it that bad, and is as good a performer as he is, it was to my benefit. I would have been a fool to not advance that one. He even brought his own make-up person to construct the older Hoover, and that was a very arduous situation putting all that on every day, it would take 5 hours to put it on, 3 hours to take it off. He’s very bright, he likes doing off-beat parts. He’s interested in roles that stretch imagination. I think that’s very admirable, I like that.

Throughout your career, I’d imagine you’ve come into proximity with people of enormous power, politically and otherwise. How did you take those observations that you’ve made from your own experiences and apply them to Hoover’s story?

Clint Eastwood: Well, with people in high office, they go into the extreme, which is absolute power and absolute power corrupts and what have you, so there’s always the corrupting thing with the 48 year stint as the director of the Bureau of Investigation. And because he formed it all and he had the trust of various executives along the way, they just relied on him and nobody could remove him. We at least approached it from that way, there are so many parallels in society today that you can use, whether it’s the head of a studio or a head of an organization, a major newspaper, a major factory or company, of people who stay too long, maybe, and overstay their usefulness.

The nature of the storytelling is non-linear, the way it shifted through the different time periods. Why did you think that was an important or an effective way to tell the story?

Clint Eastwood: I found it interesting. That was Lance’s original impression of the way to put it together, and I found it interesting that way. It was an interesting way to go back and forth in time and show him and his present day attitude and how he was when he was younger, just starting out with all kinds of vigour and ready to roll. I think we stuck pretty well with the formula and it seemed clever to me. By the same token it helped to justify all these characters. Hoover, I’m sure, felt that he was right in everything he did and even the things that we don’t like about his character. Everybody always feels that they’re right even if they’re wrong, and that’s what a whole actor’s career is built around – rationalizing your way into whatever character you’re playing. So it was great fun.

Then Helen Gandy, for instance, I’m just deviating a little bit but I’ll get back to it. When I went to the FBI, she was sort of legendary as far as running the place, and even Robert Mueller who’s the director today says, “Oh yeah, Helen Gandy, she ran the place.” She was one of those women that there were quite a few of in those days that would come into a job and after a period of time everybody would come and go and pretty soon everybody was relying on her. We listened to the tapes of her talking to the Congressional Committee after Hoover passed to the whereabouts of all of the so-called files. She stood her ground and you could tell she was somebody who was very confident after 50 years of being on that job. Nobody could burn her down. She just had her story and she stuck to it. Those kind of characters all made it interesting. You get this collage of people that all come from a different place. You ask yourself about Hoover and his relationship with Helen Gandy and his relationship with Tolson, where did it come from? With Tolson, was it just because of lack of trust? Other people come and go and rumours fly in a big organization like that. He had one or two people that he trusted and that was the extent of it probably.