Marat/Sade: The play that began a stage revolution

There was a time, hard to think of it now, perhaps, when the Royal Shakespeare Company was both radical and waggish. The billboards in August 1964 outside the Aldwych Theatre – then the RSC's London home – offered the public details of two new plays: "The Persecution and Assassination of Marat as Performed by the Inmates of the Asylum of Charenton under the Direction of the Marquis de Sade by Peter Weiss; and Eh? by Henry Livings."

That was the long and the short of it. The first play, generally known as Marat/Sade, was a dispute on the French Revolution, and an assassination story as filtered through a chaotic performance in a lunatic asylum in 1808; the second, a North Country, hilariously satirical attack on political power.

The RSC is reviving the first as part of its 50th anniversary season at Stratford-upon-Avon, but it sounds more like a reassessment than a celebration. The director, Anthony Neilson, a brilliant, improvisatory dramatist well known for his own Livings-like surreal takes on the cruelty and banality of everyday life, is thinking about the Arab Spring.

Halfway through the rehearsal period in Stratford-upon-Avon, he tells me that he is going for a more abstract, contemporary approach to Weiss's play; that he hasn't spoken to Peter Brook, who directed the original RSC version; that he is replacing Richard Peaslee's great score with a new Iraqi musical setting; and that he promises a few shocks.

"I have very big shoes to fill," he says, "but I don't mind trying them on. One could do a very respectable 'radical' production that would exist in aspic; but I felt I had to catch the spirit of the thing, and revisit it in a contemporary way. I'd rather go down in flames than rescue a masterpiece."

Brook's unforgettable production remains a signal event in the post-war British theatre, the absolute ensemble highlight between his granite Beckettian King Lear with Paul Scofield in 1962 and his definitive, white gymnasium A Midsummer Night's Dream in 1970 – at which point he left the British theatre and worked and travelled with actors of all nations, settling in Paris.

Those three productions remain unsurpassed in the annals of the RSC – pace Peter Hall's Wars of the Roses, David Warner's Hamlet, Trevor Nunn's Macbeth with Ian McKellen and Judi Dench locked in murderous conspiracy, Adrian Noble's The Plantagenets with Ralph Fiennes on fire – and Marat/Sade is particularly important: in effect, it launched the fringe and alternative theatre in this country, representing an intersection between European theory and new British radicalism.

That daring period in the RSC's life was partly curated by an American director and critical polemicist, Charles Marowitz, who was Brook's assistant in the Theatre of Cruelty season (formulated according to the precepts of the crazed poet and director, Antonin Artaud) which the RSC founding director, Peter Hall, had instigated, with Brook, at the London Academy of Music and Dramatic Art, Lamda.

Marowitz, who had become seriously and artistically involved with Glenda Jackson in the Lamda programme, pointed out that the contemporary connection between the socio-political work of the break-out RSC group and Marat/Sade was a sketch they'd presented, in the Cruelty season, about the "society whore" Christine Keeler and the "political Madonna" Jackie Kennedy.

Both were represented in the sketch by a naked Jackson – at the very start of her blazing career, long before she became a Labour MP – descending into a tin bath and emerging in prison clothes only to be harangued by lawyers and politicians. This performance was stunningly transformed into Jackson's Charlotte Corday in Marat/Sade, in which she whipped poor old Marat with her long hair before killing him in the same tin bath.

It's very hard to invoke this production without sounding nostalgic. It changed the lives of most people who saw it, including future innovative artists such as Mike Leigh and David Hare. People as different as Marowitz himself and the right-wing critic Bernard Levin hailed the breathtaking boldness of Brook's production, which used no props, no black out, but insisted on an environment – brilliantly designed by Sally Jacobs – of grey benches and sunken baths.

You can still "smell" this production in Brook's 1967 film, which was made in just 17 days, surely a record: Jackson as a fantastically erotic Corday, Ian Richardson as a maundering Marat (posed in his bath like the Jacques-Louis David portrait) and the unrivalled Patrick Magee as a controlling De Sade; it's one of the best "theatrical" films ever made.

And, at the end, the audience on film who are watching the movie rise up and destroy the theatre in a potent metaphor of future cultural priorities; the inmates take over the asylum and undermine the artistic message and commitment of the actors, just as the Marquis de Sade suggests they should.

Anthony Neilson sees it differently, however, suggesting that Brook's production was far more tasteful than if De Sade himself had done it. "We want to remind people," says Neilson – a great friend of the RSC artistic director Michael Boyd, and son of the distinguished Scottish actor Sandy Neilson – "of the RSC's radical history; and I am more than aware of the smothering shadow that Shakespeare has on the effect of new work."

This is a peculiar notion: that the Bard is inhibiting the new playwrights, when the opposite should be the case. At Shakespeare's Globe in Southwark, for instance, the artistic director, Dominic Dromgoole, has been doing exactly what Peter Hall's RSC was supposed to do, and did – mixing Shakespeare with "new epic" Elizabethan /Jacobean-style drama from Howard Brenton, Nell Leyshon, Ché Walker and Chris Hannan.

The first Marat/Sade had a direct bearing on the RSC's classical work, certainly in defining the character of the company and its approach to the emotional lives of Shakespeare's characters; Jackson's Ophelia in the following year, opposite David Warner, was the first modern, sexually distraught reading of the role, and set the standard, and the way of acting the part, for all our Ophelias since.

Brook had insisted that the actors immerse themselves in madness as it was before 1808 – before drugs and before treatment, and when a different social attitude towards the insane made them behave differently: "For this," he said, "the actor had no outside model – he looked at faces in Goya not as models to imitate but as prods to encourage his confidence in following the stronger and more worrying of his inner impulses... He had to cultivate an act of possession."

The shock of seeing a stage full of catatonics, schizophrenics, paranoiacs and manic depressives was overwhelming; none, except Marat, could "remember" the script, so they needed constant prompting. Marat declaimed his speeches as if he were already dead. The music was clangorous and jagged, with cymbals, bells and an organ. The actors performed the songs in a Brechtian cabaret style, disrupting the play and banging on the set, pouring buckets of blood down the drains during the mass guillotining sequence.

The play was not seen again in London until 1989, when the National Youth Theatre celebrated the bicentenary of the French Revolution with their patron, Prince Edward, sitting in the audience. The haunted, puritanical, bath-bound Marat was played by none other than a 20-year-old Daniel Craig, and very good he was, too; I even said he grew in stature through the evening. The play stood up, too, and so, especially, did the lyrics and music of Mitchell and Peaslee.

Since then, we've had a somewhat tepid revival at the National Theatre, directed on the Olivier stage by Jeremy Sams in 1997, with Corin Redgrave as Marat, David Calder as De Sade, a striking Anastasia Hille as Corday, and Clifford Rose reprising his 1964 role at the RSC as the director of the asylum; and a far more successful, though far too modest, "fringe" version as the opening production at the Arcola in Dalston, east London, ten years ago.

Neilson is probably the most radical theatre-maker in the country, so is well placed to deal with the improvisatory "jangle" of Marat/Sade, noting that the bath house setting when empty is a sort of Auschwitz and well aware that the "We want our revolution now" side of the show chimed exactly with the height of the American civil rights movement. He relishes, too, the fact that the play was the prize exhibit in the "dirty plays row" initiated by the producer and theatre owner Emile Littler, who was a governor of the RSC at the time.

"There's a huge gulf in the play, or our version of it," he says, "between what you hear and what you are seeing, but audiences are more than capable of dealing with that. This is why the theatre is so important, and so different from other forms of media. You can run ideas and meaning in parallel; there are no rules. We are switching references, and looking at ways in which De Sade prefigured Freud, and the way in which Freud in turn was utilised by capitalist societies."

That is not a message coming from the sponsors, but Neilson seems interestingly caught on the play's central idea of a prescriptive clash between the claims of individualism and social revolution as a key to human freedom. "If we take De Sade as a role for our society, the most compelling ideological argument is the one we are having with the Middle Eastern fundamentalists rather than the Communists." And there will, of course, be lashings of violence and nudity.

'Marat/Sade', Royal Shakespeare Theatre, Stratford-upon-Avon (0844 800 1110) 14 October to 5 November