As he approaches his 75th birthday on Monday, Harold Pinter appears frail and gaunt, leaning heavily on a walking stick decorated, somewhat incongruously, with sparkly stickers. When we meet to celebrate the unveiling of his latest work, Voices, he tells me: "I'm exhausted, I'm at the end of my tether," and admits that he is "not writing anything much at the moment". His formerly stentorian stage voice is notably weakened - a consequence of his battle with cancer of the oesophagus over the last three years. But in Voices, a 29-minute musical-dramatic collaboration with the composer James Clarke, his creative voice rings out as powerfully as ever.
This latest work by the indefatigable playwright will be broadcast on BBC Radio 3 on his birthday. In February, Pinter appeared to herald his retirement as a playwright, announcing with characteristic terseness: "I think I've stopped writing plays now... I've written 29 plays, isn't that enough?"
But there was never really any danger that Pinter, a self-professed "bit of a pain in the arse", was going to bow out of the limelight for good. Far from it; he declared that he had "found other forms" and added: "I will continue to write what I write until the day I die."
It may seem that Pinter has been rather busy writing for a retired playwright, but Voices has in fact had an elephantine gestation period. It began with a letter written by Clarke to Pinter after the composer saw Ashes to Ashes in 1996. Clarke explains: "I feel a great affinity to his way of thinking. That's why I wanted to work with him. He is a composer of words and I am a composer of music, but we have a lot in common."
The two met in 1997, intent, in Clarke's words, on "formulating a work which would use words and music in a new way". As a result, in Voices Pinter's sparse script is combined with Clarke's radiophonic score. So long has the project been on the boil that Pinter cannot recall the initial spark of inspiration. "We entered into this together some considerable time ago. I don't really remember how it came about, but we certainly found ourselves getting married, as it were. It's been a very, very remarkable, happy marriage," he says.
Clarke claims that he was attracted by the "musicality and precision" of Pinter's plays. Indeed, the composer and playwright seem to be a creative match made in heaven. Clarke is a contemporary composer who argues that "it is not the role of new art gently to massage the ears" - an uncompromising attitude matched only by Pinter's assertion that "it is one's obligation not to give the audience what they want, but insist that they take what we give them".
Voices has been a labour of love and Pinter is evidently delighted with the result. "I believe James and I have created a rich and serious piece of work in Voices, of which I am very proud," he tells me. He is grateful to Radio 3 for its patience and for "believing in it over a very long period of time", and to Ned Chaillet, the producer, "whose determination and conviction have brought this to the boil. I take my hat off to him," the playwright finishes with a flourish. For Voices, Pinter has reworked five of his later plays - One for the Road, Mountain Language, The New World Order, Party Time and Ashes to Ashes - into a fragmented narrative on cruelty, torture and oppression, which is interrupted, accompanied and complemented by Clarke's mercurial score, performed by the BBC Symphony Orchestra, the soprano Eileen Aargaard and an Azeri singer, Fatma Mehralieva, among others. Nine actors, including Douglas Hodge, Anastasia Hille, Roger Lloyd Pack and Pinter himself have reprised the roles they performed previously at various London theatres.
Describing a rather harrowing artistic journey with Clarke, Pinter uses a typically potent turn of phrase. "We both walked together into hell. Not just my hell, or his hell, but the hell that we all share here and now." The plays from which he has culled his lines share a preoccupation with the power relationship between bully and victim, torturer and tortured, master and slave. Against a backdrop of unspecified totalitarian states, Pinter focuses on interrogators, torturers and guards and their violent mistreatment of innocent prisoners.
In One for the Road, the protagonist is Nicolas, a whisky-sodden interrogator who has brought in a family for questioning (and, it is implied, raping and torturing). In the short, sharp shock of The New World Order, we eavesdrop on a conversation between two torturers, held over the top of their mute, blindfolded victim's head ("We haven't even finished with him. We haven't begun."). In Ashes to Ashes, the interrogation of Rebecca by Devlin takes a sinister turn as we learn that her ex-lover participated in state-sponsored violence. In Mountain Language, a sadistic guard plays power games with a group of mountain dwellers, who are forbidden from speaking in anything but the language of the state. In Party Time, Pinter lampoons the smug security of the middle classes, portraying an insufferably Úlite party which carries on regardless of the violence and terror on the streets outside.
Martin Crimp uses the same technique to convey the current political situation in his latest work at the Royal Court, Fewer Emergencies. Even without Pinter's evocation of today's "hell", it doesn't take a giant leap of faith to hear echoes of the current political climate in all the plays woven into Voices.
As such, Voices represents Pinter's new direction, as set out in his "retirement speech". "I've found other forms now. My energies are going in different directions, certainly into poetry. But also, as I think you know, over the last few years I've made a number of political speeches at various locations and ceremonies. I'm using a lot of energy more specifically about political states of affairs, which I think are very worrying as things stand."
In the past few years, Pinter has been seen more frequently on the podium than the stage, firing off speeches on everything from Iraq ("an act of premeditated mass murder") to the Milosevic trial ("Nato is itself a war criminal... as much as Milosevic is") and the bombing of Afghanistan. At the 2003 anti-war march in London, he rallied marchers with a rousing criticism of Tony Blair and George Bush ("The United States is a monster out of control... The country is run by a bunch of criminal lunatics, with Blair as their hired Christian thug") and his poem "The Bombs": "There are no more words to be said/ All we have left are the bombs/ Which burst out of our head."
Political art may be a relatively new direction, but Pinter's anti-establishment credentials stretch back to 1949, when he refused to do national service, declaring himself a conscientious objector. In 1996, he rejected a knighthood from John Major's government. Last month, he was one of the most high-profile signatories on a letter to Tony Blair urging him to pull troops out of Iraq.
While Pinter's "political" works are frequently compared unfavourably with his early plays, such as The Birthday Party and The Caretaker, they display the same fascination with the violence that simmers under everyday interaction and man's inhumanity to man. In particular, the abuse of language and its use as a weapon is revealed as one of the most contemptible characteristics of human nature and contemporary politics. He has described it thus: "I think what we're talking about is an extraordinary, fundamental hypocrisy and a misunderstanding of language altogether - or a distortion of language, or abuse of language - which is in itself extremely destructive, because language leads us, politically it leads us into all sorts of fields... What I find really dangerous and, shall we say, disgusting, is where the kind of language used recently - humanitarian intervention, don't forget freedom and democracy and all the rest of it - actually is justifying simply assertive acts to control power and keep power." These sentiments underpin much of Voices, in which language is manipulated by the powerful to subdue the powerless.
While Clarke is in no doubt that Voices is a political work, "speaking out against oppression of any kind", the question of genre is more tricky. Clarke is adamant that it is not simply a play set to music. He says: "Taking an existing play and making it into an opera is not something I could do, and I'd defy anybody to do it successfully in the case of somebody like Pinter. For me, it's already music... composed with words as opposed to notes. I think of them as musical compositions already, and they're incredibly precise and well crafted in every respect. I couldn't 'add' music to it. I admired his work so much, I wanted to see if there was a way of doing something with words and music which wasn't simply a question of adding music or setting a text, but building a complex, musical-dramatic work which would be new and would find some solution to this question."
The result does not necessarily solve the question. For Pinter aficionados, Voices recalls the situations and characters of the original plays, allowing listeners to play a rather intense game of spot the quote. For others, Pinter has distilled the essence of these plays, crystallising their atmosphere of menace and fear. His famously economical turn of phrase has been stripped back yet further, with the result that every line hits the listener like a punch in the stomach.
Radio is not new territory for Pinter - he wrote his first radio play, A Slight Ache, in 1958 - and there is little doubt that as a medium it is eminently suited to his style, where each word is hand-picked for maximum, often disturbing, effect. The metallic voice of Lloyd Pack's mountain guard, rasping: "It's forbidden," jars with the hazy recollections of Rebecca from Ashes to Ashes (played by Hille), watching "the man I'd given my heart to... tear all the babies from the arms of their screaming mothers".
Later, Pinter as Nicolas (One for the Road) interrogates Indira Varma's imprisoned woman. His words: "This is my big finger. And this is my little finger. Look. I wave them in front of your eyes. Like this. How many times have you been raped?" are all the more sinister for the plummy tone in which they are delivered. Jimmy from Party Time (played by Harry Burton) opens and closes the work with his haunting account of isolated incarceration ("I see nothing at any time any more. I sit sucking the dark"). To begin with, the music acts as a menacing soundtrack to the script, with clashing cymbals and jangly, atmospheric sound-effects. Elsewhere, Pinter's famed harsh insults ("motherfucker" and "fuckpig") are caught up in a sweeping choral arrangement, and Rebecca's recollections of her cruel ex-lover are accompanied by a soaring, tremulous female aria. Among the most evocative moments are the fragments from Mountain Language in which the old woman's lines are echoed in the score by a female Azeri singer. "It represents another musical language," explains Clarke. "The Azeri singer has been allied to the voice of the old lady who can't speak the official language of the capital and the instruments are allied to the guard who is telling her that her language is forbidden. There's one hell of a battle going on."
Clarke was given free rein by Pinter after the playwright delivered the script to him in 2000, and Pinter is visibly moved by the final result. "James Clarke entered into this enterprise boldly and courageously and he has done something quite remarkable," he says. Certainly, it is a brave man who sets to work on Pinter's carefully crafted prose. "I have a great deal of respect for texts and words and writers. I don't normally set texts. All my other works are abstract music," says Clarke. It must have been reassuring for both parties that the two artists share similar tastes in music, including admiration for the work of the contemporary French composer Pierre Boulez (whom Clarke describes as "precise and economical") and Bach.
Clarke describes how he decided to make the voices of the actors involved "crystal clear", although, traditionalists will be pleased to learn, the playwright's trademark silences remain. "There are many possibilities - other composers have used texts where the words are fragmented or sung. In this, the end result is closer to a radio play. I wanted to do that, it wasn't imposed on me."
According to Clarke, "it would be possible to play it live" as a musical composition, and Pinter tells me that he too harbours hopes of seeing the work performed live on stage. Clarke says: "The aim was to do something that was not so easily categorised. So maybe it will be interesting to see what people eventually do call it. If you imagine four points of the compass with music, words, theatre, opera, it's somewhere in the middle. It's certainly a musical work, but it's also a dramatic work." Whatever you want to call Voices, it is impossible not to listen to what they are saying.