Jon Stewart is best known as the host of Comedy Central's The Daily Show - the success of which has seen him become one of the most influential figures in US politics and media. He spoke to PATRICK GRAFTON-GREEN about his new film Rosewater - his first as a writer and director - which premiered at the BFI London Film Festival on Sunday.

"I have always wanted to sit in a director's chair. I just think they're very comfortable, but if you're not a director you're typically not allowed to sit in them" was Jon Stewart's inevitably jocular response when asked about his first foray into film making, Rosewater, at its London Film Festival premiere on Sunday.

The American satirist, comedian and host of The Daily Show also penned the screenplay for his directorial debut, adapted from journalist Maziar Bahari's memoir, Then They Came For Me.

It tells the story of Bahari's harrowing capture, incarceration and torture by government officials while working in Iran reporting on the 2009 general election. During his detainment Bahari's captors cited an interview he had done with Daily Show correspondent Jason Jones, part of the explanation for Stewart's involvement.

This Is Local London:

Stewart told News Shopper: "Maziar and I became friendly after he was released and his memoir is so compelling and well observed and analytical and beautiful that I was honoured he would trust me to even try and tell it.

"Part of what's interesting about him is his ability to compartmentalise the experience and I think what allowed him to write such a compelling memoir is, it's funny, the lesson is don't arrest journalists because they are trained to remember s***. 

"They pay attention, they analyse, they have an eye for articulating the parts of their experience that you don't want people to know and his ability to do that is what makes him compartmentalise it."

Bahari spent 118 days in prison, and during that time was slapped, beaten and psychologically tormented, repeatedly being told he would die in prison or be executed.

His release finally came after an international campaign fronted by his wife, pregnant at the time with their daughter, and supported by various media organisations and Hilary Clinton.

Bahari, who is played by Gael Garcia Bernal (The Motorcycle Diaries, The Science of Sleep), was involved in the shooting of the Rosewater - in Jordan last summer - at times finding it tough to relive the experience.

This Is Local London:

Stewart said: "On set there'd be moments I would say 'Maziar come here, come here, is this what the cell looked like and is this how they hit you' and then for a second I'd be like 'oh my God, I'm that guy making him relive it'.

"But it was the moments with family that were much tougher for him, the scenes that we did with him and his sister were the ones that I think he had much more difficulty with, in terms of emotionally."

Talking about what he learned from making the film, Stewart added: "I honestly feel like the best thing I learned from it is to trust your discomfort, to never be afraid to admit your shortcomings, to hire people around you that really know what they're doing, to have them raise flags, red and otherwise, as often and as early as possible.

"Your best ability is to be able to recognise when somebody's got a great idea or when one of your ideas is s***, and you don't want to waste everyone's time in pursuing it."

The 51-year-old now returns to his duties on The Daily Show - each episode of which is watched by millions.

Although a satirical show, under his guidance it has established itself as a legitimate source of critical examination of American political and media culture, and current events. 

This Is Local London:

Talking about the state of modern news, Stewart said: "We've created these sort of 24 hour seven day a week huge infrastructures for news that are really built for catastrophe, for earthquakes and 9/11, and that's when they are appropriate.

"But in the absence of those grand stories, rather than go into hibernation and appear when needed, I think that they incentivise now sensationalism and urgency.

"They have to take ordinary news and amplify it to the level of catastrophe, and so it's created this incredible momentum towards urgency and fear and war and it's been a really destructive force for American politics in general."

He added: "Apart from that though, it's really good. Good sports coverage."