This range of producers and high productivity signal both a remarkable adaptability and a spirit of generosity, because rather than slotting into an established niche in the scene of British post-war culture - where probably, for example, he could easily have become a highly successful lyricist in the Cameron Mackintosh stable -he has often chosen to inhabit the in-between worlds of collaboration, adaptation, translation. This creative inclination is matched by the formal adventurousness of his plays and screenplay, which combine populist conventions with a celebration of anarchic individualism and the desire to tell a good tale well with an impish delight in teasing the audience through unexpected shifts of register. So his theatrical work resists easy classification in its sometimes wild mixing of genres and its penchant for wrenching comedy out of horror, human warmth out of the most damning scenes of late-twentieth century despair. In reaction to this messy aesthetic anarchism, the critical establishment has tended to identify Mitchell mainly by his impressive performance as a poet, especially through his public readings: he is the British father of today's performance poets. But this conventional view misses something of the main point of his career as revealed by his playwriting: for he has created a unique role as well-liked agent provocateur, as an up-beat entertainer who deals with the nastier sides of life, a genial dream-weaver who never pulls his punches. As a highly talented ghost writer of scenarios for the Western - and particularly British - psyche, Adrian Mitchell has been nothing if not radical.

He was born in London on 24 October, 1932, to Kathleen Fabian and James Mitchell. His education took place in the lower reaches of the English private school system, first at Greenways School, then at Dauntsey's School in West Lavington, Wiltshire. Like John McGrath and most other men of his generation, the transition from school to university was interrupted by two years as a National Serviceman in the British Army. (1951-2) From the army, he progressed to Christ Church College, Oxford, where he was active as a poet, in his final year editing the university literary journal, Isis. He graduated in 1955 with a degree in English and spent the first few years of his working life as a junior journalist, first with the Oxford Mail (1995-7). Then with the London Evening Standard (1957-9), a role that put him in a prime position to follow the antics of the Angry Young Men of the generation just before his own. He has continued to write frequently as columnist and reviewer for a wide range of London-based magazines and newspapers, including the Daily Mail, Women's Mirror, the Sun, the Sunday Times, Peace News, Black Dwarf, and the Guardian - an eclectic list that says much about his radical agenda. In 1961-2 he became involved in Arnold Wesker's ill-fated Centre 42 project, alongside John McGrath and Doris Lessing, reading his poetry at the regional festivals of the arts set up by the Centre. In 1963 he had poems published in A Group Anthology, alongside George MacBeth and Peter Redgrove, a volume partly pitched as a literary riposte to the decorous gentility of the Movement poets. But it was in 1965 that he made a significant breakthrough as a public figure by resonantly voicing the growing intensity of his generation's resistance to America's war in Vietnam and all it signalled about the sickness of Western civilisation.

Three events in that year positioned Mitchell in the vanguard of the alternative society under construction by the first youthful counter culture: the inaugural Writer's Night in the basement of the radical London bookshop, Better Books, when he shared a platform on "The theatre and its future" with Peter Brooks and John Arden; the International Festival of Poetry in the Albert Hall, organised by the sigma group of poets, and featuring international underground luminaries such as Allen Ginsberg and Lawrence Ferlinghetti, alongside new British voices such as Christopher Logue, Tom McGrath and Mitchell; and his adaptation of the text for Peter Brook's breakthrough production with the Royal Shakespeare Company of Peter Weiss' The Persecution and Assassination of Jean-Paul Marat as Performed by the Inmates of Charenton under the Direction of the Marquis de Sade.

Much has been written about Marat-Sade as a ground breaking production by Peter Brook which captured the angst of a generation caught between Vietnam and drug-induced visions of a revolutionised wrold, but its theatrical fireworks have tended to blind historians to the felicities of the text that Mitchell forged from the original German of Peter Weiss. In John Elsom's Post-War British Theatre, for example, references to the show are sprinkled liberally through several chapters, but there is no mention of Mitchell as its writer. Yet audiences were roused as much by the supple poetics of the language as by the sight of Glenda Jackson as Charlotte Corday whipping Patrick Magee's Marat with her lovely long hair. Among the text's many theatrical strengths is the best post-war anthem to the new revolutionary mood: "What's the use of a revolution/ Without general copulation, copulation, copulation."

This yoking together of the political and the personal exactly captured the drive for a fresh way of being radical of the counter-cultural generation, and anticipated its theatrical apogee in the Living Theatre's Paradise Now, by several years. It was a skill that Mitchell was to exercise even more forcefully in Peter Brook's next and notorious production, the collaboratively created anti-war show US for which he is credited with the lyrics. If the superior gallows doggerel of Marat/Sade gave audiences a delightful shock, the agit prop assault of US was disturbingly outrageous, working well beyond the bounds of the good taste of its middle-class audiences at London's Aldwych theatre. Albert Hunt, who was a key figure in its making, provides a fascinating account of the show's gestation as an anti-Vietnam, pro-peace provocation, rightly claiming that Mitchell's poetry "connected with the generation made aware of words by developments in pop music" in elusively complicated ways, such as in the famous poem To whom it may concern: "I was run over by the truth one day/Ever since the accident I've walked this way/So stick my legs in plaster/Tell me lies about Vietnam." It was Mitchell's own reading of this at the hastily organised International Festival of Poetry at Lond's Albert Hall in June 1965, excellently captured in Peter Whitehead's film Wholly Communion, that had established him as the radical voice of a generation in revolt. But while by all accounts its power in performance as part of US was undeniable, the theatrical context created by Peter Brook and his adoring critics has tended to neuter its message for history. Accounts of the final moments of the show on its opening night may be seen as talismanic of Mitchell's ghostly status in British playwriting, as it has easily eclipsed his radical impact on the production: the actors release live butterflies from a box, apparently catching one and setting fire to it. The audience on the first night sat stunned into silence, prompting the critic Kenneth Tynan to call out to the cast who stood looking accusingly out into the auditorium: "Are you waiting for us, or are we waiting for you."

So Mitchell's early association with Peter Brook has not worked to the benefit of his reputation as a playwright, despite some singular successes in the succeeding decades. In the seventies we could count his first solely-authored play as the first among these. Tyger: a Celebration of the Life and Work of William Blake, produced by the National Theatre at the New Theatre, London (1971), set scenes from the daily life of Blake against vigorous song-and-dance lampoons of contemporary public figures, and well-judged quotations from the poems soared against a wildly fantastic moon voyage undertaken by the great poet-dreamer - a mixing of genres that probably had its subject wriggling in his grave with delight and certainly pleased the London critics. Despite this, the show was a worry to the National's director Laurence Olivier, if only because the New Theatre season was a financial flop. It was to be more than a decade before Mitchell was invited back to the National, but in the meantime he wrote a series of shows which were staged but the emerging popular and political theatre companies and which met with very solid success in the British regions.

The new rough and ready context of alternative theatre gave Mitchell much more scope for formal innovation, as can be seen in the contrast between the television and stage versions of his 1972 anti-colonial play Man Friday. Originally commissioned by BBC1 as a "Play for Today", it was written as an ironic interrogation of white colonialism, with the story of Robinson Crusoe retold through the eyes of Man Friday for his tribe to judge. In the process of writing Mitchell "realised it could work on stage if the audience could be persuaded to represent the tribe", and this is how it was staged by 7:84 (England) Theatre Company for a national tour in 1974. The play became a Brechtian lehrstuke, but with none of the austerity of the original form as practised by the long-dead cigar-smoking master. Instead there was rousing music by Mike Westbrook, some amusing slapstick with "primitive" props, and a bantering up-beat interaction with the audence/tribe as Friday gradually, and humorously, demonstrates that Crusoe's mission to civilise the tribe is nothing less than an imperialist rape done in the name of nationalism, the law, and private ownership. The popular trappings are diverting, but they also draw the audience into a performative structure that exercises a sophisticated dialectic, enabling them to review their own history through the eyes of the oppressed other. Audience participation of a more conventional kind was incorporated into the surreal revamp of Hamlet set on a double-decker bus that Mitchell wrote for the Liverpool Everyman Theatre in its populist heyday under the direction of Alan Dosser. Mitchell has described Mind Your Head (1973) as like "a patchwork quilt being waved vigorously like a flag…sewn together with two of our best known legends, Hamlet and Hitler." The patchwork includes Hamlet's soliloquy done as a Frankie Howard monologue, parodies of pop songs and comic patter, and characters named after famous jazz musicians, for example, Biscuits Beiderbecke and Gumbo Gillespie. But again the music-hall and panto-style fun, like the u-shaped bus of the set, is a vehicle which delivers serious stuff from the nightmare of the twentieth-century. Similar dark material was woven into Mitchell's later work in the 1970's, such as his 1976 adaptation of John Berger and Jean Mohr's book about refugees in Europe, The Seventh Man, for Foco Novo Theatre Company. Other adaptations during the seventies included Gogol's the Government Inspector (1974 - as The Inspector General) and stories by mark Twain under the title White Suit Blues (1977). Popular format shows included and Amsterdam production of Houdini: A Circus Opera (1977) and the touring tent show, Uppendown Mooney, commissioned by the most imaginative of the alternative groups Welfare State International, in 1978. The two shows for children that more or less framed the decade - Tamburlane the Mad Hen (1971) and The White Deer (1978) - are further useful reminders that from the start his theatrical commitments were catholic in reach, so that adaptations and collaborations easily outnumber plays he authored alone, and this gives some explanation for the acute eclecticism of style. But the empathy for children in both his playwriting and poetry, which has continued throughout his career, indicates an angle to his radicalism which makes it especially disconcerting. There is nothing of the idealisations of revolutionary romanticism in his alignment with the young, rather there is a hard-headed appreciation of their ability to see through adult bullshit, particularly of a political kind. And there is a celebration of unhampered creativity which produces a childlike sophistication of form: popular, fragmented, switch-backing between ditties and sombre songs, jokes and horrid facts, topical material and classical sources, but always carrying hard hitting political messages about the iniquity of the status quo, the absurdities of politicians, and the injustices of a western world getting richer by doing violence on poor people with few means of defence.

In the 1980's Mitchell stuck steadfastly to this broadly un-programmatic approach to theatre-making and almost double his output of the previous decade, from 1983 creating at least two shows a year. His adaptations ranged from Ibsen (Peer Gynt- 1980) to Kipling (Mowglis Jungle - 1981), and form Dylan Thomas (A Child's Christmas in Wales - 1983) to Lope de Vega (Fuente Ovejuna - 1989). They also included three plays by Calderon - The Mayor of Zalamea (1981), Life's a Dream (1983), and The Great Theatre of the World (1984) - the second of which, directed by John Barton for the Royal Shakespeare Company in Stratford, saw Mitchell back in a national theatre, and this was followed by two very successful shows at the National Theatre itself, where he wrote the lyrics for Peter Hall's highly effective Animal Farm (1984) and revised his adaptation of Gogol's The Government Inspector (1985). None of these adaptations was in any way slavish, as Mitchell has a telling penchant for the impact of colloquial verse and is fond of fracturing narratives. So he fillets the famous "troika" scene from Dead Souls into the climax of The Government Inspector to terrific airborne effect in Richard Eyre's National Theatre production, as Khlestakov literally flies off into the wings. Similarly he heightens the wrenching humour of Calderon's bleak visions by packing them with the everyday punch of bluntly rhyming slang. The gritty quality of Mitchell's playwriting in the 1980's matches the populist range of venues which staged his work. For the shoe-box-sized Tricycle Theatre in North London he wrote C'mon Everybody (1984), a rock and roll, show; the Calderon adaptation of the same year was done for the touring Medieval Players; his play about the French avant-garde composer Satie Day/Night (1986) was staged at the Lyric Theatre Hammersmith; while Anna on Anna (1988) was done at the pioneering community venue, Theatre Workshop, in Edinburgh. His writing specifically for children diminished in the decade, to be replaced in large part by a sustained search for forms which would combine a popular appeal across generations with themes that grappled with the darkest human dimensions of the late-twentieth century.

In this respect the short adaptation of King Lear which he wrote for Welfare State International in 1982 is quintessential Mitchell. The Tragedy of King Real was first staged as a live interlude as part of Scarecrow Zoo, a tapestry of celebrations at South Hill Park Arts Centre, Bracknell. In the following year he turned the script into a screenplay (re-named as King Real and the Hoodlums) which became the basis for a community feature film that Welfare State made mostly with unemployed young people in Barrow-in Furness, a remote town on the South Cumbrian coast whose main business is the making of nuclear submarines. This was an audacious move, as the story of Lear is retold as an out-and-out nuclear parable. Egged on by the Hoodlums, played by the youth of Barrow as a medieval-punk-rabble, King Real hands down the keys of power to his daughters, Raygal, Gonilla and Cloudella, though the last, true to the original, refuses her share. The two wicked sisters throw Cloudella out into the wasteland with the court musician, Thomas, and retire with Real and the military champion Adderman to their nuclear bunker. After an orgy of eating a huge cake of the globe, they surgically remove Real's eyes and torpedo him out of the bunker before starting the third world war. Real staggers across the post-nuclear landscape and eventually finds the dying Cloudella, who, in a scene of extraordinary poignancy sings him an explanatory lament: "You were Father Christmas/And I longed for you/You were the hangman/And I hid from you/ You were the ice-cream man/I worshipped you/You were the scissorman/ I dreamed of you/How could I love you /When I always knew/ I was the unicorn/In your private zoo." This is the woman/child's-eye-view of the twentieth century nightmare of people hopelessly trapped in an insanity made by a few privileged others, but it is also a gesture of hope because even as Real and Cloudella die it echoes out a profound resistance as it is sung by a still living young person from the town that is forced by iniquitous economics to make the nightmare.

In the first half of the 1990's Mitchell's prolific writing for the stage abated somewhat though it still covered a good range of venue types and styles of production. He continued his work on adaptations with Vasilisa the Fair (1991) in New York, and four years later a sequel to Tyger in Boston, appropriately called Tyger Two (1995). In the UK another adaptation, A New World and the Tears of Indians (1992) was staged by the Nuffield Theatre, Southampton, and he returned to work for the children's Unicorn Theatre with a Beatrix Potter adaptation, Tom Kitten and his Friends (1996). He wrote three plays for student production at the Dartington College of Arts in Devon, Unicorn Island (1992), Meet the Baron (1993), and Sir Fool's Quest (1994), based mostly on his successful story-books for children. But one of his most adventurous projects, for a highly unusual venue, also provided a new radical focus. The Blue (1992) was the inaugural production of Walk the Plank Theatre Company, which had created Britain's first theatre ship by converting the rear deck of a Scandinavian car-ferry into an auditorium, the rising rear decks of the ship becoming a multi-layered stage. The play is written in broad panto-style doggerel and tells the tale of a misguided Professor Pinkerton who, to impress the vainglorious King and Queen, is on a maritime expedition to capture the creatures of the Blue for scientific purposes. Wave and Seagull are sea-souls fished from the deep, who have to be taught to speak by a computer, so that they can reveal the secrets of the Blue, the better for humans to exploit them. The contortions of the plot end up with Pinkerton marrying Wave then killing Seagull, but Wave gives birth to Seagull's Blue Baby, who the King and Queen want to auction off before it wrecks their Kingdom. Blue Baby is saved by the ship's cook Maudie, a kind of panto-dame friend of the Blues and Wave and Baby are magically transported back to their rightful element in the mouth of a whale. In performance, in a wonderful coup de theatre, a huge whale rose up from below deck on the ship's car lift, vent spurting water, its great blue mouth grinning in delight. The production was full of such effects with, for example, the Blue Baby being swung in from above in the cradle of the ship's crane, and the huge puppet figures of the King and Queen towering above the audience on the promontories of the uppermost deck. But the good fun, and the witty writing, were skilfully tuned to the deeper purposes of the play, which, without ever getting preachy, drew powerful ecological lessons about the connections between pride and pollution, aggression and self-harm, knowledge and the devastation of the natural world. The ironies created by Mitchell and Walk the Plank's highly imaginative use of the ship-theatre carried a powerful, and profoundly radical charge.

The Blue nicely represents the unassuming adventurousness of Mitchell's approach to writing for performance, both in its commitment to populist venue and its inventive aesthetics. It is this aesthetic restlessness, the continual refusal to settle into an easily identifiable creative format, which has produced difficulties for the critical establishment. Frequently working to commission on tight deadlines, habitually revelling in the twighlight zone of adaptation and collaboration, regularly drawn to unusual venues and groups beyond the mainstream of theatre culture, always committed to a populism whose accessibility disguises its own high levels of linguistic and structural skill, seeming often more of a poet than a playwright - Mitchell has forged his own unique niche in British theatre. From this perspective the standard accusation that his is a deliberately throw-away art with little lasting value is understandable but wrong. The criticism rests on old-fashioned literary values that miss the point of his kind of performative writing, which rightly sees in the fleeting moment of theatrical impact the strongest force for change. It also fails to recognise that a diversity of output which encompasses national theatres and children's theatres, well-founded mausoleums of high-art and shoe-string touring fit-ups, traditional panto slots on proscenium stages and visionary multi-media extravaganzas on the back deck of a ship, is a generous embrace of social and cultural difference. In contrast, sustained and solid recognition for Mitchell's theatrical and literary achievement is signalled by the string of writing posts he has held in Universities (including Cambridge) and theatres (in the UK and USA), and by the literary prizes he has won. So the educational and theatrical establishments have amply recognised his stature as a wonderfully talented writer of his own kind, who has successfully side-stepped the danger of being trapped in a reputation focused only by his stunning success in the sixties. He has done this through his commitment to the graft of making popular styles of performance which reach out to many kinds of people, without ever reneging on his creative roots as a leading underground rebel, a genial agent provocateur who has always stayed true to his political lights -championing equality, justice and freedom - in order to become a singular and truly radical democratic ghost-writer to the nation. In these desperate times, when even as I write (December 1998) US and UK military planes are again bombing Baghdad, more urgently than ever we need writers like Adrian Mitchell to haunt us into sanity.