With over 70 plays and a lifetime of political activity behind him, Dario Fo was awarded the 1997 Nobel Prize for Literature. The citation reads, 'With a blend of laughter and gravity he opens our eyes to abuses and injustices in society and also the wider historical perspective in which they can be placed.' Dario Fo is a great writer but he is also an outstanding actor, mime artist and musician. As well as his scripted work, he is an improviser of sketches about current political events. In addition to theatres, his performance spaces have included factories, football stadiums and public spaces.

The citation also makes reference to Fo's translator, Ed Emery, who works 'by staying close to the original text and retaining Dario Fo's allusions.'

Ed Emery reckons to spend most of his time working for the revolutionary communist transformation of society. He studied Greek and Latin at school, and then at Cambridge. Those being the years of hot protest, he stood for president of the nascent Cambridge Student Union and tore up his finals papers as part of a protest against the exam system. He has done his fair share of factory-gate leafleting and shares Fo's taste for anti-clericalism and scatology, having once been arrested for 'obscene behaviour in an ecclesiastical precinct' (a protest at St Paul's cathedral, for Chilean political prisoners), and having produced the only human turd ever to be thrown in the House of Commons (in support of Irish political prisoners). Ed Emery translates from a multitude of languages, and is slowly working through a project of translating the entire collected works of Dario Fo and Franca Rame.

I have a stormy relationship with my bosses — Dario and Franca, I mean. Periodically they sack me and cast me into outer darkness, but then we argue and shout, and now I have been appointed their more or less official translator into English. I love The Devil in Drag. It's a terrific piece for kids, really — devils going up people's bumholes, cardinals eating horse-shite and ladies on stage with inflating tits. Dario has a great reputation as a Leftist political playwright, and when you look at his work as a whole, it's a truly amazing, wonderful, funny, humane outpouring of stuff. He's thoroughly educational too — a mine of historical information and understandings about theatre.

At the start of The Devil in Drag there has been fire in the cathedral of a Renaissance Italian city. The Judge is determined to nail the culprits. His inquiries lead straight back to the church hierarchy and big power interests represented by the Cardinal. The Judge appears to be incorruptible. He is also so repressed sexually that he is able to resist the advances of the girl Jacoba, sent by the Cardinal to seduce him. The Cardinal is as corrupt as he wishes the Judge to be. In order to ruin The Judge he gets him blind drunk, so that he ends up naked in bed with Pizzocca. The plan to ruin the reputation of the Judge is to be helped along by infiltrating a tiny devil up his backside, but this goes farcically wrong when the devil enters by mistake the body of Pizzocca, the Judge's elderly housekeeper. Pizzocca then fluctuates between wanton depravity and horror at her actions. Working with The Inquisition, the Cardinal contrives the death of witnesses who know the true story and the Judge is put on trial for fornication. Finally, as the Judge is removed from office and sentenced to be a galley slave, he casts off his inhibitions and declares his passion for Pizzocca.

For Ed Emery the story of the Lion and the Donkey is a key moment of the play's meaning. On a journey to the top of a mountain, the powerful lion persuades the donkey to carry him, saying they'll take turns. He reckons if he gets hungry, he can always eat the donkey. When it comes to the donkey's turn to ride he keeps slipping off, but then he finds a way to stay in place, good and solid. Stiff as a ramrod, he gives a thrust of his loins, and jams himself up the lion's backside. When the lion protests he justifies himself: 'Forgive me your majesty, I can't help it - each of us has to hold on as best he can.' Here we have the familiar elements of Dario Fo's work: oppressive religion, ruling class exploitation and the triumph of the oppressed masked in deference. To add to the zest, The Judge tells the story in the style of pub joke.

The characters in The Devil in Drag are effectively stereotypes with their origins in the Commedia dell' Arte. So, for example we have the Learned Man, the Judge and the Pretty Girl. Despite this, a figure such as the Cardinal is meant to summon up images of corruption today — the corruption not just of churchmen but of all those in power who preach a moral code for others and ignore it in their own lives.

People have asked me, is The Devil in Drag a political play? In a curious sort of way, it is not. Not politics with a big P. Not like earlier Fo texts such as Anarchist and Can't Pay, Won't Pay. Here the politics is far more subdued. Take the Judge's final speech, for instance. At first sight it's downright wishy-washy — derived in fact from a passage in Aristophanes. On the other hand, when played in the right key it becomes a powerful plea for humanity and tolerance. And that, I suppose, is the real politics of Fo — an abiding concern for the ordinary people. Unleashing the powers of liberation, against the powers of oppression. For him, theatre can be a way of attacking those who have money and power, and having a fun time while you're doing it. And that, as much as anything, is why I translate him.