Only 84 people a night were able to squeeze into the tiny venue to see Richard Gadd's Edinburgh Fringe play Baby Reindeer, which ran for nearly four weeks in 2019.

But that low-key play – the basis of the smash-hit television show Baby Reindeer – could end up costing the TV streaming service Netflix anything up to $120 million (£92 million), plus legal fees.

In June, lawyers acting for Fiona Harvey, the real-life inspiration for stalker Martha, launched a no-holds-barred legal assault on Netflix, demanding $170 million (£130 million), claiming she had been defamed 'at a magnitude and scale without precedent'. She was also suing for, among other things, intentional infliction of emotional distress, negligence and gross negligence.

While Netflix is fighting to have the case thrown out before it goes to trial next May, Ms Harvey seems to be in no mood for surrender. This week, her legal team filed yet another amended complaint, pointing out a number of hugely significant differences between the play and the TV show, which swept the board at the Emmys last month.

According to court papers, the play, performed by Richard Gadd as his alter ego stand-up comedian Donny Dunn, never claimed to be 'a true story' as the TV show does, instead stating that it was 'based on a true story'. Additionally, it is claimed the play contains no reference to any arrest, conviction, guilty plea or imprisonment for Martha.

This, Harvey's team argues, is key because the Netflix show ends with Martha pleading guilty to stalking Donny. As she is a convicted stalker, because of a previous campaign against a lawyer, she is sentenced to four and a half years in prison for this second offence.

By contrast, in the Baby Reindeer play, she is never arrested, let alone convicted. Instead, Donny is told by police that Martha cannot be arrested as they don't believe she has committed a crime, and he's ordered to 'apologise' to her, stop 'bothering' the police and told: 'I understand the frustration but heckling is not a crime.'

In the play, Gadd's character tells the audience: 'The last experience with the police was so burning, so embarrassing that I refuse to involve them again.'

It ends with him obtaining a restraining order against her.

Harvey's team say discrepancies like these prove Netflix knew all along that she had never been convicted of stalking once, never mind twice.

According to legal papers filed by her team on Wednesday: 'The omission of the entire arc and premise of the Series, a convicted stalker returns to prison after pleading guilty to stalking Gadd, from the Play... put Netflix on notice that details about Harvey's criminal history in the Series were extremely likely to be false.'

Not that Harvey is the only one on the warpath. For I can reveal some of Richard Gadd's alleged experiences at the hands of Fiona Harvey, which have been described in sworn statements filed into court in Los Angeles, make for jaw-dropping reading.

Allegations include that Harvey told Gadd that her clitoris had fallen off because of excessive masturbation, that she sent him her 'lucky pants' in the post after he had blocked her email, as well as invitations and demands for him to engage in sexual activity.

She also allegedly complained about her itchy pubic hair.

There were also allegedly racist tirades about immigrants and an observation that she was going to the 'gun shop' and that 'if we got rid of [London mayor Sadiq] Khan everyone will sleep easy'.

Gadd also said that Harvey shoved him in the back of the neck after he confronted her about allegedly stalking a lawyer and told him that his 'big mouth was going to get him into trouble'. In his statement, he complained of her repeated 'handsy' behaviour, with her touching his bottom while he waited tables in a pub in Camden, North London, where he worked as he attempted to make it as a comedian.

In the TV series, which also shows Donny working in a pub, this unwanted sexual contact is depicted as far graver – Martha sexually assaults Donny in an alleyway, something which her team say never happened in real life. In the TV series, she is seen attacking him with a glass and gouging his eyes, which Ms Harvey claims is defamatory and untrue.

For his part, Gadd says that she was issued with a First Instance Harassment Warning letter in 2016, which cited the Hawley Arms pub where 'the victim' worked. After months of further abuse, including Harvey allegedly telling Gadd: 'If I want you dead, you are ****ing dead', Gadd says that she was issued with another First Instance Harassment Warning letter in 2017. He includes his correspondence with police as proof. This is the first time that Netflix has revealed the precise details of her contact with police.

Previously, Netflix executive Benjamin King told the Commons select committee that the show was 'a true story' and that Gadd had been targeted by a 'convicted stalker'.

He then 'clarified' his evidence in an email to the former committee chairwoman, Dame Caroline Dinenage in July, writing that 'the person on whom the show is based' was actually 'subject to a court order rather than a conviction'.

In her amended complaint against Netflix, Harvey includes her clear DBS (Disclosure and Barring Service) check to prove that she has not been convicted of any crime. The incidents in the TV show not depicted in the play include a reference to Martha waiting outside Donny's flat for 16 hours a day, including in the middle of the night.

There is also no reference in the play to Martha smashing a glass over his head, which she does in the TV series.

The complaint adds that in interviews he did to publicise the TV show, Gadd retreated from the position that it was a 'true story', which is the line Netflix used in publicity material and on screen. They note that he called it 'pretty truthful', '100 per cent emotionally true' and 'very emotionally true'. In a ruling last week in California, Judge R. Gary Klausner noted there were substantial disparities between what really happened and what was shown on screen.

He wrote: 'There is a major difference between stalking and being convicted of stalking in a court of law.' He added: 'There are major differences between inappropriate touching and sexual assault, as well as between shoving and gouging another's eyes.'

Judge Klausner did not agree with Netflix, which argued those things should be viewed as 'substantially true' because she did arguably similar things in real life.

Netflix also argued that most viewers would understand the claims made in the show to be 'not factual' because it was shot in the style of a drama. The judge disagreed, writing: 'While the statements were made in a series that largely has the trappings of a black comedy-drama, the very first episode states unequivocally that 'this is a true story', thereby inviting the audience to accept the statements as fact.'

Netflix also said the similarities between the real and fictionalised people were so broad that average viewers would not have been able to identify Ms Harvey as Martha. The judge disagreed. Netflix is appealing the ruling.

The judge did side with Netflix in parts of Ms Harvey's case, dismissing her negligence and gross negligence claims, and her request for punitive damages.

As both high-powered teams of lawyers prepare for the next round of hostilities, some observers think the time has probably come for Netflix to settle with Harvey.

This month a mediator, Gail Title, was assigned to the case. Netflix has to submit a mediation questionnaire to her by Tuesday next week. Could the off-screen drama be finally nearing a close?