Genesis P-Orridge photographed by Christophe DemoulinThe omens were not good from the start. It was late Sunday afternoon in May and a thunderous black sky had been drenching the good people of Dalston for most of the day. Christophe Demoulin, the photographer, and I were lost on the unusually long rubbish-strewn High Road as we searched for the venue where the interview was to take place. We didn't know it then but the weather would mirror our chilly reception later. Eventually we found it: an unsigned, anonymous black door sandwiched between a restaurant and a Turkish café. Once inside, stairs led down to the basement club - your bog-standard, sticky-floored, low-lit rock dive. I looked for the "manager" whom I had only been able to contact via email and who identified himself by the hip-hop moniker "Matski", so I was expecting a young black guy in a designer hoodie. Instead, a lanky bespectacled hippy in his 50s wearing tartan granddad slippers was leaning against the otherwise deserted bar. Usually before a gig there is a buzz about having the artist in the house, a nervous energy, a repressed air of excitement. This was to be the only date rock singer and art house provocateur Genesis P-Orridge was to play in the UK, on a short European tour, under the umbrella of his solo project PTV3, and it had sold out quickly. So why was there such a curious lack of occasion in the air?

Though his name is unknown to the man in the street, Genesis P-Orridge does enjoy some degree of infamous notoriety in a certain demi-monde. For 30 years he has been an underground cult figure, with a reputation for outrageousness, showmanship and mystical depth that he has assiduously cultivated. His legend rests primarily on the work of the two bands he formed, wrote for and sang with; Throbbing Gristle, the 1970s pioneers of the proto-punk industrial style, and the 1980s psychedelic occult band Psychic TV. But in addition to the music P-Orridge is also widely feted as a performance artist, visionary, courter of controversy, disciple of Charles Manson and Jim Jones, occultist and self-inventor. Recently he has been enjoying something of a revival among a younger generation who have discovered his music and performance "art" on the internet.

When I made myself known to the hippy propping up the bar, "Matski" confirmed with an American drawl that, yeah, he was the manager, then carried on chatting to his pal. Eventually, I butted in to ask when and where we were doing the interview and it became clear that he hadn't given either question any thought. Then he ambled off to "do something" while we stood by the bar and waited.

I passed the time reviewing what I knew of our interviewee's background. Born and bred in Manchester, Neil Megson attended art school in Hull where he first came up with the name Genesis P-Orridge, eventually changing it permanently by deed poll. A typical product of English art colleges, he immersed himself in conceptual art and actionist theatre, dedicating himself to making political gestures designed to challenge and destroy bourgeois convention. A follower of the philosophies of William Burroughs, Brion Gysin and Aleister Crowley, Genesis, through Throbbing Gristle, Psychic TV and his numerous side projects, borrowed much of their imagery and inspiration from these transgressive giants. Throbbing Gristle's manifesto was to shock and disturb the audience as much as possible with taboo-busting shows featuring mutilation, totalitarian symbolism and S&M imagery. They set up their own record label, Industrial Records, which had a photo of the Auschwitz gas ovens as its logo. Everything was designed to provoke, from Cosey Fanni Tutti, the female guitarist, being a stripper and porn actress, to Genesis dressing as a Nazi or a priest, and live shows featuring transvestites, punks, street whores and used tampons as "found" art. Childish and naïve as much of this was, there's no denying it felt radical at the time.

Genesis has long been interested in body modification. In fact, he was one of the first people I met with pierced genitals. Since then he has moved on to the terrain occupied by the likes of Orlan, the infamous French performance artist who uses plastic surgery as her medium and not for the purpose of prettification. Genesis's latest attention-seeking "performance", along with his late wife, Lady Jaye, was for them both to undergo extensive surgical enhancement with the aim of looking as alike as possible and the intention of creating a third person or unifying into one hermaphroditic being. He coined a new phrase for this: pandrogyny. Judging from the photos I have seen this new entity looks remarkably like a cut-price drag queen. He now sports breast implants, collagen-plumped lips, a bad blonde dye job and make-up designed, it appears, to make him look something like the beautiful junkie singer Nico from the Velvet Underground. This radical surgical overhaul for a man of 60 shows he remains true to his original motives: anything to shock the "world into thinking a bit for itself" - both admirable and yet strangely infantile. Even more odd is his take on it: "I deliberately chose to distort the DNA of my body as a rebellion against predestination."

Back at the bar, still cooling my heels, I chatted to Christophe, who had just rushed all the way from Paris for the shoot, and had once been an assistant to Orlan as well as being a cameraman on several gay porn films. Knowing Genesis's obsession with plastic surgery and his long-held interest in pornography and prostitution (Throbbing Gristle caused public moral outrage with their infamous 1976 ICA show "Prostitution", for which one Tory MP condemned them as "wreckers of civilisation"), I thought he would be interested to meet Christophe. As we waited patiently, I reminisced about the "Gen" I had once known.

It was 1983. I had just turned 20 when I first met him through my then boyfriend, the cartoonist and rock musician Mark Manning, aka Zodiac Mindwarp. It was Gen who had encouraged him to get his first cock piercing, a "Prince Albert". Gen believed that Mark's piercing proved that Mark had bought into the new cult Gen was forming around his band Psychic TV. But Mark told me the only reason he'd had it done was because it provided a great chat-up line. Well, it worked with me.

When I eventually met Gen I was a girl-about-town, hanging out with fellow freaks like the ballet dancer Michael Clarke, singer Boy George and fashion designer and performance artist (later muse of Lucien Freud) Leigh Bowery, while writing for the Face magazine - so influential then that a mention secured a record deal and instant cool credentials. Genesis seemed eager to cultivate me.

He began inviting me to his home, a damp Victorian terraced house in Beck Road, Hackney. It was usually because he had his latest track to listen to or "something" to show me. I found him interesting: well-informed, quick-witted, possessing a keen intelligence and always with plenty to say. But he was also pompous in the extreme. It was difficult to take seriously someone who took themselves so seriously. He wasn't merely a singer and lyricist, he told me, but a "linguistic engineer".

One day Gen announced he had something "interesting" for me to watch. It turned out to be a gory but entirely convincing snuff movie (fake, I discovered years later). Then there was a real-time film of an execution by electric chair where smoke plumed up from the man's head and his eyeballs boiled. While these unwholesome vignettes played on the video, Genesis watched me watching them like a naughty schoolboy gleefully waiting for his maiden aunt to scream at the plastic spider. No stranger to shock tactics myself, I deliberately disappointed him, feigning a yawn.

The P-Orridges mostly occupied the upper two floors of the house. The main room on the ground floor was used as their sexual playroom, which they called "The Nursery". It was cold and smelt of piss, with whips, chains and instruments of torture hanging off the walls. A coffin sat in the middle of the room and the prize possession was an old dentist's chair, which Gen claimed had belonged to a dentist in the 1950s who was jailed for raping his female clients. He offered us the privilege of use of this grim dungeon. When I told Mark about the invitation, he snorted: "Not chuffing likely. I know the dirty bastard's drilled a hole in the ceiling so he can watch."

Gen's predilection for voyeurism was confirmed on another visit. In the bloody aftermath of the acrimonious disbanding of Throbbing Gristle, Genesis set about forming a new band, Psychic TV, which was less a rock band than a conscious attempt at forming a pseudo-religious cult, centred around the imagery of Satanism and sex magick (the misspelling an homage to Aleister Crowley) with a sizeable dose of "Satanic Majesty"-era Rolling Stones.

Fans of Psychic TV were invited to join the Temple ov (sic) Psychic Youth - for a fee. Twenty-three was chosen as a sacred number following William Burroughs' discovery of the esoteric "23 enigma" (Psychic TV are in the Guinness Book of Records for producing 23 albums in 23 months, all released on the 23rd day of that month). It was aimed primarily at disaffected youth, and its followers seemed to be mostly teenage boys at boarding school who were lonely, angry and looking for a cause. And easy to manipulate. To be initiated the wannabe Psychic Youth had to send in samples of his bodily fluids on the 23rd day of every month: blood, semen, saliva. Along with these, they had to write down in detail their masturbatory fantasies while being solemnly assured that these would never be opened or read, instead being placed in a vault for posterity. I saw with my own eyes what happened to those spotty youths' naive outpourings of their newly dawning sexual yearnings: Genesis and Paula opened them, read them aloud, pissed themselves laughing then invited the boy whose photo they found most appealing to stay with them. Paula seduced him while Gen watched. It's one way to keep a marriage going, I suppose. After witnessing all that, no wonder At Home With The P-Orridges was firmly burned into my memory.

Back at the club, Genesis had still not put in an appearance so I brought Christophe up to date. While visiting America in the early '90s with their two daughters, Caresse and Genesse, Genesis and Paula heard that Hackney social services wanted to question them about allegations of child abuse. (Despite his carefully projected image that there were no boundaries, I don't believe for a minute that Gen was inappropriate with his girls.) Their house was raided by Scotland Yard's Obscene Publications Squad, who unearthed their vast collection of occult writings and graphic photos of anything involving murder, necrophilia, mutilation, sexual deviance and Nazi imagery. In short everything that illustrated Genesis' fascination with the power and mechanics of evil. The couple didn't dare return, and instead went into self-imposed exile in San Francisco. Divorce followed not long after and, in 1993, Genesis met and married the woman he has described as the love of his life and soulmate, Jacqueline Breyer.

A former nurse almost 20 years his junior, Jacqueline quickly became another of Gen's projects. Jacqueline - who reciprocated Gen's ardour, by the way - morphed into "Lady Jaye" and became collaborator in his artistic endeavours. Then came the worst and the best thing to happen to him. In 1995, a fire broke out at American record producer Rick Rubin's home while Genesis was there and he sustained substantial injuries escaping from the inferno. A US court awarded him over $1.5 million in damages.

Genesis put his swollen bank account to work immediately. He had all his teeth removed and replaced with solid gold implants, the procedure filmed and presented as art in the more gullible galleries of New York. And he began paying for major plastic surgery for himself and his wife, to create the third being, the pandrogyne. Then, two years ago, Jaye died suddenly of an unknown pre-existing heart condition that could have been exacerbated by all the surgery. In videos posted on the internet (the latest form of manifesto) he seems genuinely heart-broken, lost.

Suddenly, out of nowhere, a short figure in a dirty white muslin dress materialises before us. Those large bloodhound eyes rimmed in kohl regard me with hostility, his over-pumped lips painted in '60s frosted pink lipstick turned downwards in a sulky pout. I stepped forward to say hello, asking him if he remembered me. "Why should I remember you? I've met about 385,000 people in my life." Oh. I shifted from foot to foot, feeling embarrassed. I tried to jog his memory, repeating one by one the same memories I had just recounted to Christophe. Each tale was greeted with chilly annoyance, with Genesis Breyer P-Orridge (the middle name a trace of the lost third being) getting increasingly more irritated and denying all knowledge of any of the episodes.

Only once did he let his guard down: when I mentioned his daughter Caresse, his expression softened and the proud dad emerged to inform us that she was getting married the following week. The entire encounter was strange and awkward and deteriorating by the minute. I smiled at him, touched him (her? them?) on the shoulder and said, "I'm surprised you don't remember me. A bit upset actually." Whereupon Genesis replied, "Well, if you feel like that, we won't do the interview" and flounced off back to the tiny cloakroom doubling as a dressing room. At first we thought it was a prank, a mini "happening" to keep us on our toes but, after seeking out the elusive Matski and sending him off to speak to Genesis, he returned to tell us with a shrug that she was serious. One of the Throbbing Gristle slogans was "disappointment guaranteed" and Genesis certainly lived up to his promise that night.

We did return later for the gig, which I have to admit was surprisingly good in an even more surprising conventional rock n' roll way. Gen's been smart enough to install a first-rate drummer and guitarist, so tight that they stop the rest of the band, two superfluous blondes dressed like young Nicos, from falling apart. Gen sang with his trademark nasal Northern whine and played violin a la John Cage, but delivered an oddly static performance. His memory must be appalling because he needed to refer to his lyric sheet throughout the set. Matski doubled up as sound man and the only time Gen talked to the crowd was to introduce them to his manager, who he called "my bitch".

An encore - a stonking 15-minute rendition of the Velvet Underground's "Foggy Notion" - finally succeeded in getting the whole club rocking. No accident surely that he chose a song by the band from which he has lifted most of his best ideas. Some days later someone pointed out to me that if watching snuff movies and exploiting teenage boys was such an everyday occurrence in the P-Orridge household that he had forgotten it, perhaps Hackney social services did have reason to be worried, all those years ago.

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