Or, the Marat/Sade to be concise; not that concise is a word that comes to mind when thinking back to Wednesday’s preview. At a good hour and three quarters before the break, having just witnessed a feast of anal rape, the interval Shiraz should be available through the NHS.

But I’m giving away the plot. Actually the (full) title tells you all you need to know. The Marquis de Sade really was imprisoned at the asylum in Charenton and really was allowed by the director Coulmier to stage plays acted by the inmates. So the story created by the writer Peter Weiss is a perfectly legitimate fantasy, and it was originally produced in the UK by the RSC as part of their Theatre of Cruelty season in 1964.

Herr Weiss is no longer with us so we cannot tell what he would have made of the liberties taken with his text. It’s certainly been updated, with additional speeches by Marat, Roux and the Herald (there may be more); his descriptions of his characters’ attributes and their costumes have largely been ignored; and Weiss was very minimalist with his stage directions, which allows the director Anthony Neilson, pretty much Carte Blanche to do what he wants.

Some of these liberties are very successful. Coulmier controls the inmates through a system of mobile phones and the piercing sound of ringtones has a startling effect throughout the play. A dangerous ploy – it would kill the atmosphere if a phone accidentally went off in the audience. Marat himself prepares his speeches using a laptop in his bath – in fact the whole production couldn’t have gone ahead without the late Steve Jobs. The Herald is no longer a male clown-cum-harlequin, but the role is performed by an actress with restricted growth who often uses an electric wheelchair to move around the stage. She’s quite an arresting sight, and often has a glint in her eye that she can turn to evil effect; it’s a very good performance from Lisa Hammond.

Mrs Chrisparkle, however, is less charitable of the director’s motives. Her reaction to the production was that he had a checklist of faux offensive activities he wanted to ensure were included, and that he wouldn’t be satisfied until every one of them was ticked off.

The programme makes much of the play’s parallels with the Arab Spring of today and its relevance to the 21st century. There are some excellent lines (in the original text) about having trust in “our minister of war” and also the irony of “calmly watch these barbarous displays that could not happen nowadays”. All that on the week that Colonel Gadaffi was killed. You couldn’t make it up. It’s true that the play hasn’t dated at all – I think it was probably always timeless. There is some surprising use of the hijab, and Khyam Allami’s stirring and atmospheric music for the production lends an eastern lilt to the play. The four asylum inmates who act as singers in the production are in excellent voice and contribute to making the music one of the highlights of the play. I particularly enjoyed the performance of Amanda Wilkin as Kokol.

In fact one of the really strong points of this production is the excellent ensemble work of the actors playing the inmates. They provide a really credible image of they type of people who might inhabit an asylum – their walks, their tics, their habits are all well observed and totally believable – apart perhaps from Lanre Malaolu’s Duperret, who really does masturbate an awful lot (tick). I felt that was probably only so they could often call him a “w**ker” (not in the original text) (tick), so I’m not blaming him.

Whether it’s the play itself or the specific production, it’s hard to determine, but I have two main problems with the show. Firstly, it’s way too long, particularly in the first half. A lot of that is Weiss’ fault. In the text, the first act covers 69 pages, the second act, 30. But there’s a lot of self-indulgent activity in the first act that could either be completely removed or drastically cut down – the anal rape (tick) scene goes on and on, and on… and on. One feels that he’s proved his point; now can we get on to something else please. Many of the speeches by Marat and Sade are very heavy and wordy – to the extent that you stop paying attention and focus on the stage activity instead. As they haven’t treated the text with reverence, I think it some of these speeches could have done with extra pruning. The result of all this is that there are many sequences that are just plain boring.

Secondly, basically, it’s a play that hates its audience (which is one of my pet hates). A member of the audience gets approached by one of the cast which results in their being called a c**t on stage (tick). Members of the cast variously insult and moon at the audience (tick), people have popcorn chucked at them like a weapon, a black actor turns to a white man in the audience and says “Death to the White Man!” (not in the original text) (incitement to racial hatred? Tick), the dildos that are used in the anal rape scene are then waggled in the faces of elderly ladies in the front row (tick). I’m sure you get the picture. There is a moment when Marat walks down an aisle asking patrons if any of them can speak French, because he wants them to translate something for him. Only a fool would offer to help, because God knows what trick would have befallen that person. I certainly kept schtumm, as did everyone else. It’s up to you to decide whether this is a legitimate way of challenging an audience, or if it’s merely taking the Mick.

Having said that, one thing I did like at the end of the first act was how Arsher Ali’s Marat started deconstructing the piece. Voltaire and Lavoisier do their interminably dull speeches to the audience and frankly no one is paying any attention, at which point Marat says, “you’re losing them, it’s no good, stop now, they all want the interval, they all want their ice-creams” and then he starts to go around the front row taking ice-cream orders. Nice. That’s what I call subversive, much more than the bizarre over-use of jockstraps (although that did reveal a curious tattoo of a map of Africa on one person’s buttock).

What of the main roles? I wasn’t quite sure what to make of Jasper Britton’s Marquis de Sade. Weiss’ description makes it clear that he should be an imposing figure. But I didn’t find him that imposing. I found him very human, very flawed; to be pitied rather than to be in awe of him. They’ve made him into a cross-dressing chameleon, taking on a different persona almost every time he comes on. I wasn’t very convinced by him as an American cowboy; but he was absolutely right as Mary Portas. There’s also a scene where he comes on dressed as the Herald, in her wheelchair, and with shoe attachments on his knee so that he can mimic her stature when on all fours. In the first act her character abused an audience member who had been tricked into patronising her disability. In the second act, the production itself patronises her. You can’t have it both ways, Mr Director. Which is it to be?

Christopher Ettridge’s Coulmier is every inch the respectable director and on the face of it a world apart from the general madness surrounding him. The coup de theatre at the end is effective but not in keeping with Weiss’ original; and it’s been done before in Rocky Horror. Actually, the whole meaning of the end of the play is changed – in the original version the play ends in total anarchy with Coulmier attempting to restore order by striking his patients much to the delight of the Marquis de Sade who glows with pleasure at the mischief. Not so in this production. I also very much enjoyed Nathaniel Martello-White’s performance as Jacques Roux, who has a very commanding presence, natural authority and moreover a voice as clear as a bell. This is his RSC debut season; I think he could become a bit of a star.

Imogen Doel as Charlotte Corday looks very much the part, but I couldn’t always understand the words she was saying; and this production has the character played by an inmate with sleeping sickness (which is quite funny) whereas Weiss described her as a somnambulist. Do you think someone ought to have checked the dictionary definition?

Arsher Ali as Marat was very convincing, spoke clearly, and I admired the clever make up job that makes him look like he’s had part of his head shaved. Was it entirely necessary to have him sitting on the toilet at the beginning of the second half? Was it just so that one of the inmates could smear themselves in his excrement? (tick).

A number of people left at the interval. To be fair, a play like this isn’t doing its job properly if at least some people aren’t motivated to prefer their own more polite company. The audience reception at the end was more rapturous than I expected, although a lot of it was from some whooping girls who had got more into the sex and nudity elements of the evening than might otherwise be deemed dignified.

So in conclusion I’d say yes to its still being relevant; yes to its ability still to shock; yes to the overall standard of acting; but no to a feeling of overall satisfaction. A plucky failure? Probably, but often that can have more artistic value than an unambitious success.