A few weeks before the Max Clifford case came to court, I visited him at his home in Surrey. The Guardian hoped to make a film about his trial, to be shown at its conclusion, but he declined the request on the grounds that he wasn't the emotional type and wouldn't provide the tears and tantrums he thought we wanted. He gave a pacey run-through of the charges he faced: 11 counts of indecent assault against seven teenage girls, aged 14 to 19, between 1966 and 1984. They were all rubbish, he said. It was obvious from one woman's description of his office that she had never been there; another said that he had abused her in his car at a time when he had no car and hadn't even learned to drive… And on it went.

There could be only one motive, he thought: the promise of publicity and money. After all, nobody understood the world of kiss'n'tell better than he did. As far as he was concerned, it wasn't a question of if he got cleared, but when. And when he was, boy, was he going to give Operation Yewtree – the police investigation into historic sex offences committed by Jimmy Savile and others – a piece of his mind.

Clifford's house, on a private road in Hersham, was so pristine; it looked like a show home. He showed me the outdoor heated swimming pool where he swims every day, introduced me to his housekeeper (he was taking her for dinner that evening to celebrate her birthday). He was rough-hewn charm itself. His second wife and former PA, Jo Westwood, was "away in the country".

Halfway through our two-hour meeting, his phone rang. It always rings in meetings with him, partly because he is a busy man and partly because it gives him a chance to show off. It's normally Simon (Cowell) or Kerry (Katona) or Louis (Walsh), calling for advice. (There is no way of knowing if it really is Simon or Kerry or Louis, short of snatching the phone from him.) "Don't thank me, thank Beyoncé. Yes, darling, it's a pleasure. Yes, of course, darling, I'll tell Beyoncé how grateful you are." He got off the phone and resumed our conversation as if nothing had happened.

What was all that about Beyoncé, I asked.

"Oh, nothing," he said. This was classic Clifford: keep them hungry. When pressed, he explained that he'd helped the woman caller out financially. So what did it have to do with Beyoncé? "Well, I've just been paid by Beyoncé for some work I've done for her, and I used some of that to help this lady."

But Beyoncé doesn't know anything about it? "No, of course not. But it makes her feel good to think it came from Beyoncé. And where's the harm in that?"

Clifford seemed resilient. But then he started to talk about the £1m-plus he had lost since his arrest, as the clients tailed off, and how he had learned to distinguish between true friends and the phoneys. He talked about the various charities of which he is patron – the children's hospices and cancer hospitals – and showed genuine emotion as he explained they had asked him to keep his distance until the trial was over. Nothing personal, you understand.

He quickly gathered himself before giving me a lift to the station in his silver Rolls-Royce Ghost (registration number 100 MAX). There was one thing I felt confident of: this was an Operation Yewtree fishing expedition – for all his lies and braggadocio, Max Clifford was an innocent man.

And then the trial started. As witnesses came forward by the dozen to give evidence at Southwark crown court, the pugnacious, barrel-chested bullyboy of the PR industry started to look like an old man. His jackets were spotless, his shoes shined, his sense of outrage obvious, and yet he often seemed defeated – shuffling into court, shaking his head, wearing a hearing loop that looked like a dog collar (at the end of one morning, he admitted he had struggled to hear any of the evidence). As the weeks went by, he stopped stifling his huge yawns as the case was made against him.

The trial ranged from Greek tragedy to Carry On farce. At times, it felt too strange to be true – or, as the prosecution argued, too strange not to be true. Max's Angels, as Clifford's all-female office team are known, attended on a shift basis, one at a time, sitting loyally in the public gallery as their boss was labelled an exhibitionist and an abuser. They were joined by a handful of civilians (largely retired, portly men), there on a regular basis to enjoy the spectacle. Occasionally, eccentrics walked into court: one man took umbrage when asked by the clerk to stop filming; a drunk woman sidled up to me and whispered that she had a story to sell. The air fizzed with schadenfreude.

In the dock, we saw Clifford's many sides: the loving father who straightened his back when his daughter Louise came to give evidence, giving her a don't worry-about-me smile; the caged jaguar, prowling the dock impatiently before the day began; the belligerent victim who turned his head to stare out one hostile witness as he left court; the irrepressible chancer winking at old friends who provided good character witness statements.

Most of the women who testified against him were around 50, well-spoken and eerily similar: immaculate long hair, beautifully turned out, the air of former models. Their stories provided intricate Venn diagrams of overlapping evidence. All had been teenagers when Clifford told them he could arrange for them to meet the Walker Brothers, or star in Dynasty, or in films with Charles Bronson and David Bowie, or in the James Bond film Octopussy. We heard from women who said they had visited Clifford in his office, then been sent out to receive calls purportedly from James Bond producer Cubby Broccoli, or Bronson, or Dynasty producer Aaron Spelling – all of whom appeared to be a poorly-disguised Clifford. Two women said they had been phoned by a man with an effeminate voice called Terry Denton. One girl was told by "Denton" that he didn't like Clifford, and could she find out whether it was true that he had a small penis? Another was told Denton was jealous of her because he fancied Clifford and was sure the publicist would make her a star. Clifford admitted he had used the name Terry Denton (a late friend) as a means of testing potential clients' trustworthiness. We heard from women who said they were abused in his office, in toilets, in his car, in a cab, on holiday in a jacuzzi.

Clifford's barrister, Richard Horwell, ripped into these complainants with steely eloquence. He pointed out their inconsistencies with theatrical relish: the woman who claimed to have been abused in Clifford's office, yet described a room that bore no resemblance to 109 New Bond Street; the witness who claimed Clifford had encouraged her to go for a part in Octopussy two years after the film came out; the woman who said she was abused in Torremolinos when he wasn't there. The evidence, Horwell suggested, was unreliable at best, dishonest at worst.

Then Horwell pulled out his trump card: Clifford's penis. He reeled off the contradictory evidence: it was tiny, two and a half inches erect, according to some; according to another complainant, it was huge. In fact, Horwell argued, it was average, at five and a quarter inches flaccid. This bombshell was introduced with a Cliffordian flourish: the PR man's perfectly ordinary penis had been measured by a medical expert called Dr Coxon.

There were other moments of manic humour. The witness who described Clifford's penis as huge rationalised her apparently contradictory evidence by pointing out that she had a small mouth: "My dentist always said so." At which point the jury had to be temporarily dismissed for giggling. There was the defence witness who constantly referred to him as Sir Max and believed he was the editor of the Daily Mail; when told he didn't have a knighthood, she said she was just being respectful. Clifford himself was sometimes deliberately funny (when talking about his education through Diana Dors sex parties), sometimes unwittingly so ("Why would I need to name-drop when I represented the Beatles?").

With a favourite tabloid scoop (and client files). He later admitted he'd fabricated the allegation about the Chelsea strip. Photograph: Michael Birt/Contour

The penis evidence was vital, Horwell argued, because it showed that the complainants had never seen it. Prosecution barrister Rosina Cottage counter-argued that size was in the eye of the beholder – and anyway, it wasn't the size of Clifford's penis that mattered, but what he did with it. This was courtroom drama at its finest: two contrasting QCs at the top of their game – the calm, meticulous Cottage stitching together disturbing patterns of behaviour; the waspish Horwell playing to the gallery. Cottage labelled Clifford a "master in the art of intimidation", who used his celebrity connections to "bully and manipulate" young women, treating his office as his "sexual fiefdom".

Horwell rubbished this. He said he'd hand his wig to any member of the jury who could make sense of one particular scenario, and rejected some allegations as "grubby voyeurism… fifth-rate fiction not even Mills & Boon would countenance". The reasons most of the women had given for not fighting back or going to the police at the time (they were scared, or shocked, or naive) were an insult to women the world over, he said: "Women are not stupid, were not stupid." Cottage's approach, he suggested, had been to "speculate like mad and hope the jury buy it".

This case was about more than the fall of one man. Barely two miles away, at the Old Bailey, two former News of the World editors were on trial, accused of conspiracy to hack phones. Clifford had fed the News of the World and other tabloids many of their larger-than-life stories: "Commons call girl" Pamella Bordes dishing the dirt on Conservative minister for sport Colin Moynihan in 1989; actress Antonia de Sancha getting her revenge on Tory national heritage minister David Mellor (in his Chelsea strip) in 1992; Rebecca Loos settling a score with David Beckham in 2004. For decades, Clifford (and the red tops) thrived on a cocktail of sport, sleaze and scoops. (The Old Bailey has heard that News International offered Clifford a £200,000-a-year retainer to represent the Sun in exchange for him calling off his lawyers in a phone-hacking civil claim.) Between Southwark and the Old Bailey, were we witnessing the death rattle of an era, of the kiss'n'tell, the "cheeky" sexism that runs through tabloid and entertainment culture – from Page 3 to the "old school misogyny" Rebekah Brooks detailed in her evidence?

This was also a vital case for the Crown Prosecution Service, after a number of trials for historic sexual abuse had collapsed. Coronation Street actors Bill Roache and Michael Le Vell were cleared of sexual abuse charges including rape, as was Conservative MP Nigel Evans. It was an important case for Operation Yewtree in particular, after a series of high-profile arrests had resulted in discharge. In February, Dave Lee Travis was found not guilty on 12 charges of indecent assault – though later this month he will stand trial again, after the jury failed to reach a verdict on two charges; he also faces one new charge of indecent assault. Had Clifford been cleared this week, more questions would have been asked about the wisdom and practicality of prosecuting alleged assaults going back decades. At times over the past year, it has felt as if a whole generation of minor celebrities are being tried for the sins of Savile, who is believed to have committed hundreds of sexual crimes in his lifetime without facing a single charge. Are these cases laying down a marker for the future by convicting old men for behaviour once commonplace (most of the claims against Travis were for groping)? Yet many of the alleged offences were far more serious.

I first met Max Clifford in 2001, at his New Bond Street office, where I interviewed Ted Francis, the man whose evidence helped jail Jeffrey Archer. Francis had provided a false alibi for Archer in 1986, used as evidence that he hadn't been with a prostitute; 13 years later, with Clifford's help, Francis went to the News of the World to admit he had lied. (He claimed he had not known the alibi was intended for use in court, and was cleared of perverting the course of justice.) Francis was a foolish, rather sad man, and Clifford felt protective towards him. But he didn't sit in on the interview, and didn't suggest what I should write, as many publicists do. This was the kind of story with which Clifford liked to associate himself: broadsheet-worthy, with political resonance, giving Clifford a certain gravitas.

We next met a year later, when I interviewed Simon Cowell at the same offices. Clifford was his publicist – or svengali, as he would have liked us to believe. Cowell was already famous for Pop Idol, but nowhere near as famous as he would go on to be. Back then, he obediently turned up for interviews at Clifford's office, lifted his top to show his high trousers and hairy stomach, while Clifford watched on proudly and told me that his main job was keeping Cowell out of the papers. When Cowell was asked by Piers Morgan on the television series Tabloid Tales for the best career decision of his life, he replied, "Hiring Max Clifford."

With former client Simon Cowell, who once said 'Hiring Max Clifford' was the best career decision of his life. Photograph: matrixpictures.co.uk

For years, Clifford had a prurient finger in every pie, from footballers' wives to royal affairs. In his memoir, he wrote that he had been hired by James Hewitt to keep him and Princess Diana out of the papers, before casually claiming Hewitt had confided in him that their affair had started two years before the birth of Prince Harry. Clifford often claimed there was a higher purpose to his sex scoops: for instance, his revelations about Conservative MPs in the 90s exposed the hypocrisy of John Major's family-values campaign, and helped bring down the government.

In 2002, I had arranged to interview the film-maker Louis Theroux. I wanted to follow him around as he worked, but he insisted on a formal meeting at his office. I knew Theroux was making a programme about Clifford, so I phoned Clifford's office and asked if I could meet up with him when Theroux was filming. A few days later I received a call: could I meet Max at Sainsbury's in Surbiton? Not long after I got there, I walked into him being followed by Theroux and his camera crew.

Theroux was irritated and the whole episode ended in farce, but it was typical Clifford: generous, manipulative, keen to impress me, keen to get one over on everybody.

The next time we met was almost a decade later, when I interviewed his new client Mark Kennedy, the police officer who had infiltrated a group of environmental activists and been exposed for having long-term relationships while undercover. Clifford was in clover: he knew it was a great broadsheet story – one that brought the integrity of the Metropolitan police into question and caused political embarrassment, and one that had sex at its heart. There was a camera crew in his tiny office, and Clifford bossed the room. But after a couple of hours he told us it was time to leave. "Right, that's enough. You can all fuck off now."

Maxwell Frank Clifford was born in Kingston upon Thames, Surrey, in 1943, the youngest by nearly 10 years of four children – a war baby and a "mistake". His father worked as an electrician and gambled away the family money. His mother was a huge, loving presence. Nobody tells the Clifford tale better than he does. How he left school at 15 with no qualifications; got sacked from his first job as an apprentice salesman at Elys department store in Wimbledon, for being rude to a customer; how his printer brother used his trade union contacts to get him a job as an editorial assistant on the Eagle comic. By 18, he was a trainee reporter and writing a music column for the Merton & Morden News. He loved the music industry – the celebs, the glamour, being at the hub of happening London. He also loved journalism: he keeps his NUJ life membership certificate on the mantelpiece, awarded for 40 years' continuous service in the trade union.

He was headhunted by EMI in 1962 to work in the press office, and likes to tell the story of how he was given an unknown band to work with for six months. But even Clifford admits he had little to do with the Beatles' subsequent success. In 1970, he formed his own company, Max Clifford Associates, and before long had rewritten the rules of public relations, not only providing stories, but often making them up. In court, Cottage referred to him as a ringmaster and control freak – the very words he'd used to describe himself in his revealing and ultimately self-incriminating autobiography, Read All About It.

The book was meat and drink for the prosecution. Was he a sex-obsessed philanderer? "I was too greedy to be faithful," he wrote. "Almost anything went, including having two girls at a time. Having sex with girlfriends' mothers and watching others have sex."

Clifford admitted to the jury that he'd had four long-term relationships while married to his first wife; as for the sex parties, he claimed to be just an obliging host. His book told it differently: "I became the ringmaster, a role I liked to have in many aspects of my life… The parties became my circus and various people performed in different ways."

Did he promise girls success in exchange for sex? "Often they were both beautiful and randy, and because some of the male guests were TV and film producers, they saw the parties as a way of getting an Equity card… Fortunately I knew one or two agents who would issue false contracts in return for sexual favours," he wrote. Did he lie to the girls about who some of the men were? "Sometimes I'd invite a mate along as a treat. One was a plumber, but I pretended to the girls at the party that he was a film producer. I made sure he had a wonderful time with a couple of them who thought they might get a part in his next film."

At times, he portrays himself as running a protection racket – keeping stories out of the news by making the victim of an exposé pay the girls more than they would get from the papers; or getting one man so drunk that Clifford was able to replace the woman in his bed with a man, then film it and tell him he had been with an underage teenager. At other times, he comes across as a pimp: "Sexual procuring has never bothered me as long as the people involved have been old enough to know what they're doing." As for the specialist tastes of some clients, Read All About It boasts that he provided a safe environment in which they could indulge their perversions.

In court, Clifford insisted he would never exploit women sexually, or take photographs of them topless for a kick. But again his memoir tells a different story, boasting of a bet he had with Freddie Starr (another Operation Yewtree arrest) that he could make the first woman he stopped in the street come to his office and agree to a revealing photo; he won when a traffic warden happily took off her top and told him she wanted a career in TV. For Clifford, these were dares and pranks.

He also wrote of his contempt for paedophiles. He said of Jonathan King, "I'm delighted to have played a small part in his arrest and trial. I even have a letter from the Surrey chief of police thanking me for my help in bringing him to justice. King and Glitter are typical paedophiles, manipulative and arrogant. Their arrogance is necessary for them to squash their guilty conscience. And they need to be manipulative to undermine their victims. The only difference between them and other paedophiles is that they like the spotlight, whereas most prefer to stay hidden away."

In 2011 I interviewed Clifford. He said he had never discussed the affairs or sex parties with his first wife, Liz. He had found it easy to get away with them because of his job and his lifestyle. He said he had always loved sport, and considered sex another sport, admitting it was not so much him that women found irresistible as his power. "Not only was I in the sweet shop, I owned it… For 30-odd years I was making people famous, looking after stars, going to the most glamorous places in the world, so the Hunchback of Notre Dame would have been incredibly successful sexually."

It was a Friday evening, and Clifford was meeting his daughter Louise for a charity do. As he stood up at the end of the interview, his trousers fell down, revealing a pair of sparkling white pants. He had sat behind his desk with his trousers unzipped and unbuttoned throughout. In court, Cottage repeatedly made the point that his office was his "sexual fiefdom". I'm pretty sure it wasn't that day – it was just his fiefdom. But he saw no reason why he shouldn't sit there comfortably unbuckled.

If the tabloids were ever to do him over, I asked then, what would be the worst thing they could say about him? "Well, they can't say I'm alcoholic because I don't drink." He paused, before finally saying: "They might have said I'm perverted because of a lot of the things I got up to."

For all the unintentional hilarity, there was a sadness at the heart of Clifford's trial. For decades, he'd had the Midas touch when it came to muck-raking; now everything he touched turned to dirt. Witnesses called him a "repulsive geek", and remembered his bad breath, his desperate fumblings, his diminished manhood.

Many of the witnesses he called to his defence failed him. The brother Clifford said had taught him to drive couldn't remember doing so. The pop-flop singer who had won New Faces gave an initial statement saying that they were on holiday together in Spain at a time that potentially incriminated Clifford. He then said he had got the month wrong. When it was suggested by the Crown that he was lying to help Clifford, he said he wouldn't lie, couldn't lie, and if Clifford had done any of these things, he deserved everything coming his way. A former PA (and lover) remembered the yellow Jaguar that Clifford had such trouble recalling, and in which he was alleged to have abused one of the complainants. They were trying their best, but no one could tell Clifford's story as convincingly as he could.

Leaving court after his conviction with daughter Louise. Photograph: Nicholas Razzell

Saddest of all was his daughter Louise, now 41, in the witness box. A young girl who suffered debilitating juvenile arthritis, she had belatedly taken herself off to university to get a degree and ended up working alongside her father. She told the jury what a wonderful father he had been, how he and her mother had had a great relationship, despite the affairs, how many sacrifices he had made for her. Yet even Louise's evidence was called into question: she insisted that she had only ever visited a jacuzzi in Spain – where Clifford was accused of abusing a 12-year-old girl – with her parents, only to be contradicted by the jacuzzi boss, who said Louise had sometimes taken friends. (The case was not among the charges, because the alleged incident happened abroad.) After giving evidence, Louise turned up most days to support her father from the public gallery. Clifford's wife, Jo, remained conspicuous by her absence.

One day, a member of Clifford's staff rang me. "How do you think it's going?" she asked. I told her I thought it could go either way. She sounded disheartened. "Do you really think I'd have spent six years working for a pervert?" She said they were stressful times. "All our livelihoods are at stake."

At the start of the trial, Horwell had said we would hear from a number of Clifford's famous friends, and warned that the defence had no intention of turning the trial into a celebrity circus. They were as good as their word. They called car experts, arthritis experts, penis experts, and still we waited for the celebrities. Clifford had been well and truly abandoned – there was not so much as a whisper of a guest appearance from Simon Cowell. Who did that leave Clifford to call on? In the end, actress Pauline Quirke and singer Des O'Connor came forward to vouch for him. Both knew him through charity work and as friends, and said he was utterly trustworthy, a good man who loved to help others. We heard from numerous people who talked about his charity work, as if altruism and indecent assault were mutually exclusive. Even here, Clifford had lost his touch: when we were told how "he makes dreams comes true for the children", it was impossible not to think of Jimmy Savile.

Occasionally, Clifford would try to assert his former authority with journalists. One day he popped into the waiting area to tell us, strictly off the record, why one of the jurors had been dismissed. Another time, after giving evidence about his sex parties, he poked his head in to jokingly ask a couple of female journalists if they were free that night. When he saw me standing near the women's toilet, he benignly threatened, "You look dodgy, Simon. You're loitering. I'm going to get one of the journalists to write up a piece on you. From the Independent." Yes, it was a joke, but it all felt so inappropriate, as if he had forgotten where he was and what he was being tried for. Much of the time, he didn't have the energy or will to put up a front. Waves of tension rippled through his back as he sat in the dock. At times he was breathing so heavily, you feared he might have a heart attack.

The most powerful witness was the woman who gave evidence from behind a screen, the first complainant who had come forward. She said she had met Clifford on holiday with her family when she was 15, and claimed to have been groomed by him. Her evidence was quietly convincing, as she related Clifford's befriending of her parents, his claim that she could be the new Jodie Foster, the way he told her to take off her top in his office, took her on trips in his yellow Jaguar and sexually assaulted her. When Clifford told her that a photographer had hidden in a bush and snatched photographs of her performing a sex act on him – "so close he could see your freckles" – and that the photographer was now threatening to publish, she said she became suicidal. Clifford told her he was doing his best to protect her. Most haunting of all was an anonymous letter the complainant had written to Clifford three years ago – significantly, before Savile's crimes came to light. The letter – calm, detailed, despairing – was read out in court by Cottage:

"I wondered if you remembered as I do the child sexual abuse you engaged in, befriending my parents, flattering their daughter, talking of an acting/modelling career, offices near Bond Street. They were impressed even though no one had heard of you. Conversations about your friend Tommy Steele – wasn't it squash you played? Julie Christie and the new Star Wars film that was soon to hit the cinema. Lots of famous names, places and yet still down to Earth. A local lad done good. Recommending restaurants, funny stories, little secrets you fed them to gain their trust.

"The abuse started in your office. You sat behind your desk, eventually persuading me to strip, convincing me that my protesting was ridiculous and very childish. 'Don't you want to be grown up?'

"You took pleasure in degrading me, visiting me at home, taking me out to meet fictitious people, abusing me instead and returning me with a story so my parents didn't become suspicious. Names of people we had met, places we had been to, so they would be fooled that their daughter was in safe hands and not those of a paedophile. A+ in grooming children. How proud you must be.

"What chance did I have? You made my life a living hell, up until the point when I even contemplated suicide.

"You repulsed me then as you do now, wearing the mask of someone who has values, hiding behind charity work, trying to cleanse yourself of the guilt you must feel perhaps and stating that you don't have sympathy for paedophiles.

"You say you can't bear hypocrisy and that is what spurs you on, when you yourself are a hypocrite worse than any of those you seek to shame. A paedophile who publicly condemns other paedophiles to divert attention. A double bluff…

"Part of the reason I'm writing to you is that my counsellor has recommended it as part of my therapy. I'm undecided how much it will help or where we go from here."

When the police searched Clifford's house after the woman made a complaint, the letter was found in his bedside drawer. Unsurprisingly, the prosecution suggested that this was significant. Clifford told the jury he had shown the letter to both Louise and his wife (who, it emerged in court, had secretly made a photocopy of it). If he'd had anything to hide, he said, he would have destroyed the letter. He kept it because he thought it might be a precursor to blackmail.

He had a point. Even the victim's therapist had told her the letter's conclusion might read like a threat. But she never did blackmail him. Instead, a couple of years later, she went to the police. Her parents had recently died and this was a factor in her coming forward – she had been ashamed of what had happened, and did not want to hurt them. Clifford said he thought it was a "tragic" letter, but dismissed it as having been written by somebody who was disturbed.

By now the trial was taking its toll on everybody. The jury was already down to 11 (one member had been dismissed because she knew the casting director of Octopussy), when another juror abruptly announced in court that she would definitely take Judge Anthony Leonard's directions seriously. It was a strange outburst – was she ridiculing him or just being friendly? Two days were lost when the juror went sick before being dismissed.

Meanwhile, Clifford's Angels were looking increasingly worn. One shook her head even more vigorously than Clifford as the judge summed up. Louise looked inconsolable. When the court closed for Easter, I wished her a good holiday. She looked at me as if she couldn't quite believe what I had said.

Clifford was also getting nervous. In the canteen, he bit his nails as his friends talked around him. He was overheard on the phone saying, "I'm hoping for the best and preparing for the worst." By the time we left for Easter, he had recovered his colour. I passed him as he was stepping into the lift with a big silver-haired man. Clifford stopped the lift to address me. "Simon, if you really want a scoop, you ought to do something on this fella. You could investigate him. He's the one who holds the Ukip Christmas party." It turned out to be Richard Hunt, who had indeed hosted the "Ukip Christmas ball" at his Hampshire home. (Despite calling himself a lifelong socialist, Clifford had done work for Ukip, claiming he made them electable.) For a moment, he seemed to be the old Clifford, insouciant, embarrassing, showing off that he could still throw me the bone of a story.

A week later, and the jury was still sitting. With the verdict sweepstake long done and conversation exhausted, journalists were quietly losing it in the press room. Sun reporter Chris Pollard had started a Clifford Fashion Watch to keep himself amused. The member of staff who had told me she would not have spent six years working for a pervert said she was stressed: "I'm beginning to fear the worst of all options – a hung jury and a retrial." She just wanted it over, one way or another. Only Clifford looked as if he was thriving. The longer the jury deliberated, the more he returned to his old ebullient self. As I left court on Friday last week, with no decision in sight, he called out, "Oi, Simon, you've been here every day for seven weeks and you've not written a word. Some job that is. I buy my Guardian every day, and not a word."

It was on Monday during the lunch break that everybody was recalled to court. We'd already had one false alarm that day – when the jury accidentally pressed the light used to confirm they had reached a verdict, only to announce that they needed a cigarette break. This time round, the clerk told us they were just back for a point of information. In fact, Judge Leonard announced that the jury had reached a decision on all but one count – and that was enough for him. By now the court was full, tense and airless.

Louise was dressed all in black as if preparing for the worst. Clifford wore a royal blue sports jacket with gold buttons. The clerk asked the head of the jury for the verdict on each of the 11 counts of indecent assault. Count one – no decision. Count two – not guilty. We could see the way this was going. Then came the four counts of indecent assault on the 15-year-old victim who had written the anonymous letter. Guilty. Guilty. Guilty. Guilty. There was no expression on Clifford's face as the first few guilty verdicts were announced. Then he inflated his cheeks and released his breath slowly. He was found guilty on eight of the 11 counts. Judge Leonard addressed him in a brusque manner we had not seen before: "Mr Clifford, stand up." He told him sentencing would be delayed until Friday; he was being granted bail but that was no indication that he would not go to jail.

As Clifford walked out, he put his arm around Louise's shoulders. It looked as if he needed the help, not her. Only then did the significance begin to sink in. The King of Spin was no more. Maybe Clifford will appeal, but whatever happens his reputation is in tatters. Britain's best-known publicist is likely to be remembered as an abuser and a groomer. Meanwhile, Operation Yewtree is celebrating its first significant victory. What once looked like little more than a trawl of half-forgotten gropers from long ago had successfully prosecuted serious sexual abuse.

Doubtless in prison Clifford will hand out pearls of wisdom to his fellow inmates, do deals, make friends and influence people. But public relations will never be the same in the UK – and nor will the red-top press. It's a world that was changing even before he was sent down. Post-hacking, post-News of the World, with pressure on the press to rein in its excesses, kiss'n'tell is never going to be what it once was. Perhaps there was an inevitability about Clifford's fall. Live by the sleaze, die by the sleaze.

Outside court, Clifford posed for the cameras with Louise. She raised her head to the sky, her eyes shut. "Max, will you appeal?" shouted the reporters. "Max, you said it was a witch-hunt, do you still feel like that?" "Max, have you anything to say to the women?" "Max, is it time to say sorry?"

For once, the man who prided himself on always having the perfect soundbite to hand had nothing to say.

• Clifford was sentenced to eight years in prison on Friday 2 May