In March of 1997 Rolf Harris sat down to write a letter.

It was addressed to a man he had known for decades, a former neighbour, a respected medical professional.

The man’s daughter had just accused Harris of abusing her as a young teenager.

The letter was part a confession and part a denial. It was an apology, but also offered excuses.

Harris knew it was important. But he may never have imagined it would, 17 years later, be the central piece of evidence in his sexual assault trial.

“Obviously this is a letter you will want to consider very carefully,” Justice Nigel Sweeney told the jury, shortly before they went to begin deliberations.

It began almost formally: “Please forgive me for not writing sooner,” Harris wrote.

“I have been in a state of abject self-loathing. How we delude ourselves. I fondly imagined that everything that had taken place had progressed from a feeling of love and friendship.”

He had visited the man’s daughter and “realised the enormity of what I had done to [her] and how I had affected her whole life … I fear she can never forgive me. I find it hard to like myself in any way, shape or form.”

He concluded “I know that what I did was wrong but we are, all of us, fallible and oh how I deluded myself.”

But what did he do wrong?

Six men and six women have had to make that decision.

Harris faced 12 charges of sexual assault, of four different girls, from 1969 to 1986.

The first, "R", claimed that when she was aged 7 or 8 in 1969 she went to a local community centre near Portsmouth where Harris performed for a crowd of children, then groped her after giving her an autograph.

The second, "P", was a teenage waitress in Cambridge in 1978 when, she said, she came across Harris on all fours barking at a dog – then he grabbed her bottom.

The last, Australian Tonya Lee, was a 15-year-old on a youth theatre tour of London who met Harris in a London pub in 1986 and, she said, was assaulted by him when she sat on his knee and then in a corridor outside the women’s toilets.

Harris denied meeting R and said he had no memory of meeting P or Ms Lee, and claimed he never assaulted them. He said they either made up their stories or, in the case of R, may have mistaken someone else for him.

There was little corroborating evidence, and there were no witnesses.

The jury also had to assess the stories of six "character witnesses", who said they experienced sexual assault at the hands of Harris outside Britain – their appearance at the trial was to convince the jury Harris was a bad man who, basically, did this sort of thing.

The prosecution drew up a list of features their independent claims had in common, with each other and with the complainants’, and said this made them more than a sum of their parts: a “chillingly similar” pattern of behaviour by a habitual “pervert”.

Harris denied meeting some of them, admitted meeting others but had no memory of any of them and, again, said they must have invented their stories because he was sure he never assaulted them.

Defence counsel Simon Ray said the so-called common factors were either inevitable (Harris met everyone in his capacity as a celebrity, for example), or fairly generic to the kind of sexual encounter being described.

The trial fussed endlessly over details. We read an email in which Bindi Harris pondered her £11 million inheritance; we heard debate over the existence of a white marquee on a green field 40 years ago; over the difficulty of finding decades-old newspapers; over whether Harris would ever use the word “mate”; over the interpretation of shadows and colour in a yellowing photograph. We heard multiple opinions on whether Harris’s hugs were creepy or affectionate; we got a line of character witnesses whose only real contribution was that Harris was a nice man who had never personally assaulted them.

But each of the accusers’ stories, essentially, came down to their words against his. To the jury looking them in the eye and wondering "did they make all of this up?"

We will never know which of these witnesses the jury believed, and which they didn’t, and what effect that may have had on their verdict.

We only know they decided that Rolf Harris had lied to them.

But the centre of this case has really been the story of one woman. She alone alleged more than one fleeting encounter. She was the subject of that 1997 letter. Hers was a horror story.

The prosecution said she was assaulted by Harris as a young teenager, her will destroyed, and that he groomed her like a pet to submit to his occasional sexual demands that lasted until she was in her late 20s.

The fear, guilt and anxiety turned her into an alcoholic recluse.

They said that, reading between the lines of that letter, you could tell Harris knew this and feared police action could follow.

“This is a confession of child abuse,” was the view of prosecutor Sasha Wass, QC.

But the defence painted Harris as a middle-aged man flattered and seduced by a confident but troubled young woman, who lured him into a handful of sexual encounters, and whose ruin was not really his fault, though he felt responsible.

They say the letter was excruciatingly honest and should be read at face value. He never abused her. She was an adult, she consented, their affair was adulterous, mistaken, wrong - but not criminal.

Ms "A" – her real name cannot be published – was from early childhood a close friend of Harris’s daughter Bindi. She was a shy child, partly because of a squint which had to be corrected in hospital, partly due to undiagnosed dyslexia. She was a bit of a tomboy, with two older brothers.

Her family were "proper" English; formal, reserved, "silver trolley" at dinner time – unlike the Harrises across the road, Rolf, Alwen and Bindi, who lived a more casual, artistic life and ate in front of the telly.

In late 1978 the Harris family planned an overseas trip – partly for fun, partly to fit in with his work which took him regularly away. Bindi, by now sick of this type of endless, boring travel with her parents, begged for A to come along. A was 13.

On December 19 they arrived in Hawaii. The girls shopped, sunbathed and played tennis.

One day, A said, she popped up to the hotel room she shared with Bindi to take a shower. She came out in a towel and, somehow, Harris was in the room. He said nothing, just came over to give her one of his big hugs and tickles.

The court heard a lot about Harris’s hugs. He would hug everyone, man, woman and child. They were big bear-hugs.

But A recalled finding them "cringeing". Not like her family’s "proper" hugs – “it was creepy the way he enfolded you.” He made a noise, like “oarrrrr”. He spat on his fingers, put his hand inside the towel, and assaulted her.

Soon after, at the beach, he assaulted her again, under the guise of wrapping her in a beach towel.

Harris denies all of this. He says he wouldn’t have had a key to the teenagers’ room and he doesn’t like spending time at the beach – not only did it not happen, it didn’t even make sense.

"A" said Harris assaulted her twice more on that holiday, at Harris’s parents’ home in Bassendean, Western Australia. She felt disgusted with herself but didn’t feel she could tell anyone. “I didn’t think of running [away],” she said. “I wish I did think of it. I just didn’t know what to do.”

Harris said it just didn’t happen.

The prosecution said Harris was "grooming" his victim, testing her willpower, judging what he could get away with. From then on, they claimed, he abused her over the years that followed as and when it suited him, without any love and affection, or even conversations.

The counts on the indictment, the prosecution said, were the first five encounters in a longer list, stretching until A’s late 20s when she finally moved away from London and her abuser. Before she was 16, twice he came over to her house and went upstairs to assault her. Twice he came into her bedroom when she was staying at in the Harris family home in Bray. Once he even gave her oral sex when Bindi was asleep on another bed in the same room.

But the defence said these stories had simply been made up. Harris said their relationship began when she was 18 (and he 53). He brought her tea in bed one morning when she was visiting Bray, and she threw back the covers suggestively. He was flattered, there was “sexual chemistry”. The next time he brought her tea he took up her invitation.

This was not a deep, abiding love affair, Harris said. Neither side denied around eight sexual encounters over the following decade - in a car by the side of a motorway, in a secluded lane in Bray, once in his pantomime dressing room, once at her home, even once in Bindi’s home in Devon, Harris stripping off in excitement in his own room before darting across the corridor.

The relationship “fizzled out” when A moved away from London. By then she was well on the way to being an alcoholic. One day a few years later, confronted angrily by her family over her drinking, she told them it was because she had been abused all her life, and named Harris.

The defence case was that this was a desperate attempt to deny responsibility for her decline, a cider-fuelled invention that would replace blame with sympathy. She was then forced to stick to it, they argued. She was angry with Harris at the time because he had a new lover: his lodger and housekeeper Andy Kingston.

The prosecution had scraps of evidence to counter this: a school report in which A was seen crying about family-related problems; evidence that her alcohol problems began around the time she came back from the holiday; and a memory from a schoolfriend that, aged either 16 or 18, A had confided that Harris was a dirty old man who would touch her up when she sat on his lap.

A’s mother remembered panic attacks in A’s teens and Harris going up to her room when she was 15.

The jury heard many more details of this "sporadic, illicit, somewhat low-rent adult relationship that ended in embarrassment" – as the defence described it – and “a man arrogant, brazen, who treated women and young girls as sexual objects to be groped and mauled whenever he felt like it”, as the prosecution preferred.

But this was not a case to be decided on details, on the web of evidence.

It was an assessment of character: one of Australia’s most famous sons, versus the women who came forward to accuse him.