Who said a clown can’t be mayor of a great city? Two years ago, when Dario Fo (the Nobel Prize-winning jester and satirist) launched a campaign to become mayor of Milan, one of his most vocal supporters was London’s mayor, Ken Livingstone.

“I hear now in the papers of Milan that they say this man is too utopian, he is an idealist, he is lovely, but it will never work,” Livingstone said at one of Fo’s rallies. “That isn’t true. A journalist said to me, ‘Do they talk about Milan in London?’ I said, ‘If you elect Dario Fo, the whole world will talk about Milan. You have a chance. Take it!'”

Fo’s campaign was serious, not a Screaming Lord Sutch-like piece of tomfoolery. Aged 79 at the time he became a candidate, he said he wanted to “dedicate my last years to my city, trying to make it smile once again”.

Fo’s candidacy didn’t get far; he won a little less than 25 per cent of the vote to choose the centre left’s candidate. Although the people warmed to him, the left-wing parties opted to support the former prefect of the city, Bruno Ferrante. The media didn’t pay much attention either.

The story of Fo’s campaign is told in a new documentary, I Am Not a Moderate (Fo’s campaign slogan), which premiered at the Locarno Festival this summer. The title is telling. Fo doesn’t do moderation. For more than 50 years, he has been scandalising and provoking the authorities. One might have expected the Nobel Prize for Literature that came his way in 1997 to make him more accepted in Italy, but he annoys contemporary politicians just as much as he did their grandfathers in the 1950s. Silvio Berlusconi detests him. Three years ago, Berlusconi’s party, Forza Italia, sued Fo for defamation after performances of his satirical play, The Two-Headed Anomaly, a broad farce that started from the premise that part of Vladimir Putin’s brain was transplanted into Berlusconi’s head.

That tussle was another to add to all the battles the clown and satirist has fought. His targets have ranged from the Catholic Church to the Mafia, from the US government (which once barred him from the USA) to the Italian Communist Party, from anti-abortionists to the Chinese government.

On a hot August afternoon in Locarno, where he has come to support the premiere of the new film, Fo explains being attacked by powerful figures has never bothered him. “It is normal,” he says serenely. “It proves that you are doing good.” When I ask if he’s ever felt that he would like to lead a quieter life, he roars with laughter. “I don’t want to be an old man, looking at the sunset. That’s a hateful idea, even if it is romantic. I prefer to be on the bank with the people, explaining to them what sunset is.”

Fo, a surprisingly imposing figure, learnt his storytelling technique from the old folk and craftsmen in the town on Lake Maggiore where he was born and raised. When he won his Nobel Prize, he credited them with teaching him the “art of spinning fantastic yarns” that would fill listeners with laughter but then make them pause as they recognised the tragic undertow.

In essence, this is what his career has been built on – rowdy comic tales and satires in the Commedia dell’Arte tradition, always with bite, sarcasm and irony. The Nobel Committee suggested that he followed in the tradition of “the jesters of the Middle Ages in scourging authority and upholding the dignity of the downtrodden”.

In person, Fo is a graver, more melancholy figure than you might expect. Through an interpreter, he gives concise, earnest answers to questions about the mayoral race. He doesn’t hide his dismay at what has happened in his beloved Milan under its current mayor, Letizia Moratti, formerly a minister in Berlusconi’s cabinets. “She hasn’t solved any problems,” he laments of Milan’s first female mayor, adding that her programme wasn’t “based on truth”.

You can’t help but wonder how Fo keeps his optimism. After all, 50 years of his gibes don’t appear to have done much to change Italian politics. As a teenager, he was active in the anti-Mussolini resistance. Today, he is still fighting corruption in European politics. He says that he’s fearful that further figures in the mould of Stalin, Mussolini and Hitler will emerge on the political stage, albeit in new guises.

When he received his Nobel Prize, he gave a droll but melancholy lecture entitled “Against Jesters Who Defame and Insult,” in which he lamented the ignorance of young people. He recalled that he and his wife Franca Rame (the actress to whom he has been married since 1954) had been giving seminars at universities, but when they mentioned the 1993 massacre at Sivas in Turkey, they encountered only blank faces.

“We told them about the proceedings now in course in Turkey against the accused culprits of the massacre in Sivas,” Fo says. “Thirty-seven of the country’s foremost democratic intellectuals, meeting to celebrate the memory of a famous medieval jester of the Ottoman period, were burned alive in the dark of the night, trapped inside their hotel. The fire was the handiwork of a group of fanatical fundamentalists that enjoyed protection from elements within the government itself. In one night, 37 of the country’s most celebrated artists, writers, directors, actors and Kurdish dancers were erased from this earth.”

Not only were the students ignorant of the massacre; so were their teachers. The idea that such an atrocity could take place seemingly without anyone in Western Europe noticing continues to nag at Fo. “Making people ignorant has become an art, a science,” he sighs. “Journalism is the science of not informing people.”

It’s understandable that Fo is so suspicious of the mass media. His work has always suffered censorship and interference. During his mayoral bid, TV stations simply ignored him. To find his audience, he has to meet them face to face. During his campaign, he staged a number of shows that fell somewhere between theatre and political rallies.

Often, when celebrities turn to politics, they become bores. Not Fo. Even as he has been busy provoking his enemies, he has never lost touch with his audience. A consummate performer, Fo has also established a huge following for his playwriting.

Accidental Death of an Anarchist and Can’t Pay? Won’t Pay! have been performed countless times at theatres all over the world. Both enjoyed West End runs and are frequently revived. Accidental Death was inspired by the true case of a suspect who was thrown from the fourth-floor window of a police station in Milan at the time of right-wing extremist bomb attacks. Can’t Pay? Won’t Pay! is about working-class women who rebel against rising prices by taking goods from stores without paying. These plays appeal to a general audience who wouldn’t normally be attracted to the works of a self-confessed anarcho-Marxist.

Fo is as busy as ever. He’s working on what he describes as “a story about Michelangelo, his philosophy and his way of life”. It’s one of a series about artists he has developed in recent years. It doesn’t sound contentious, but it’s safe to predict that he will find an angle that will upset someone or other. If it didn’t, it wouldn’t have Dario Fo’s name on it.