If someone asked you to think of an autistic person, who would come to mind?
The world's richest man, Elon Musk?
Maybe Greta Thunberg, who says being different can be a superpower.
Or Robbie Williams, who has recently revealed he's found out that he has "a bit of autism".
What about someone like 34-year old James Fitzpatrick? He doesn't talk, has a learning disability and needs constant care.
A diagnosis of Autism Spectrum Disorder (ASD) means someone has certain core characteristics including differences in how they communicate and behave. It's an umbrella term that includes people with very different experiences.
In recent years there has been an explosion in the number of people with an autism diagnosis on their GP record. In England, it has gone from just over 700,000 three years ago to around 1.1 million today.
The National Autistic Society (NAS) says "evidence suggests there is a significant underdiagnosis of autism, particularly among women and older people".
But what if some people with a diagnosis aren't actually autistic? What if they've really been misdiagnosed?
These questions largely come from 85-year-old Professor Dame Uta Frith - one of the key figures in autism research since the 1960s.
They go to the heart of a debate that is central to the identity of many autistic people.
Dame Uta says this is about misdiagnosis - people wrongly being told they are autistic.
She is reluctant to say how many people she thinks have wrongly told they have autism: "In my worst moments, I think it's a great number, but in my best moments, I think it is a small number."
Dame Uta is worried that autistic people who need a lot of support are not getting the help they need.
Some autism researchers and charities say her views are "dangerous", "misinformation" and pit "autistic people against each other". Many autistic people are angry too, saying this calls their identity and rights into question.
The increase in diagnoses of neurodivergent conditions such as autism and ADHD, along with a steep rise in people reporting poor mental health, has prompted a government-commissioned independent review that is due to be published shortly.
But whatever its findings, it is unlikely to be the final word on a question that affects so many people: what actually is autism? And does it matter if such a broad spectrum of people are defined as having it?
Shifting meanings
The definition of autism has shifted and evolved since it was coined in 1911. Then, it was described as a symptom of childhood schizophrenia - excessive fantasies and hallucinations.
By 1943, autism was used to describe children with "fascinating peculiarities" who weren't interested in the world around them.
In the 1960s, it was estimated that 0.04% of children were autistic and most had intellectual disabilities.
By the early 1980s, researchers embraced the idea of an autism spectrum, arguing that autistic people could have average - or very high - intelligence.
This new category of autism was known as Asperger's Syndrome after a little-known paper dating back to Austria in the 1940s, but the term is no longer used.
In 2013, ASD became the official diagnosis for all autistic people. But some autism experts think this is too broad.
Dame Uta ignited this debate by arguing that the autistic spectrum has come to its collapse because people included in it have such different needs.
Questioning the spectrum
A quick search through social media tells you that the 85-year-old is "a pioneer", "brilliant" and the "grand dame of autism research".
But also, a "traitor", an "out-of-touch grifter" who is "past her sell-by date".
During one of our conversations, she receives an email - hate mail. It tells her she will have blood on her hands and contains expletives.
She says: "Some people would say it would be better for me to stop. But I want to get at the truth."
But, even so, she hesitated for years before speaking out, partly because she "really, really" doesn't want to hurt people.
She talks about being driven by "almost a duty" to represent autistic people with intellectual disabilities. She thinks they are being ignored "both in research and in general awareness".
About a third of autistic people have intellectual disabilities. But they are underrepresented in research - a 2019 study found that they make up about 6% of research participants.
Dame Uta says: "These cases are in great need of support. They have been completely overshadowed."
She would include this group on a "pruned" autism spectrum along with people who have what used to be known as Asperger's and autistic people who are diagnosed during childhood.
She thinks the rise in autism diagnoses is driven by a "late-diagnosed group, mainly females".
The NHS says it can be difficult to recognise autism in women, but Dame Uta says: "I am sceptical of late diagnosis. That's where I think the diagnostic process has become very superficial."
She believes many of this group actually have other conditions including anxiety, depression or OCD.
She questions: "Are they best served by this label autism? I would like them to get better service than they're getting."
She also thinks researchers might need to create "a label that doesn't exist yet" for some people who've been told they're autistic.
She points to research from the University of Cambridge which found that people diagnosed with autism in early childhood often have a different genetic profile to people diagnosed when they are older. Researchers found that people diagnosed when they are older (from late childhood onwards) show an underlying genetic profile that has more in common with ADHD and depression than it does with early diagnosed autism.
But the lead researcher, Dr Varun Warrier, says this shows "autism broadening out genetically" rather than misdiagnosis.
Dame Uta thinks a small number don't have any mental health conditions at all - but are "identity seekers" who have been influenced by bad information on social media.
She hasn't got a number for how many people she thinks have been misdiagnosed, but believes researchers could figure it out.
She knows this will upset and possibly scare people. She stresses: "If someone has been misdiagnosed, I don't want them to suffer for it.
"It would be a terrible thing to take away a diagnosis retrospectively. It's the future I'm concerned with, making diagnostic process more precise - targeting very different individual needs rather than a label."
Culture wars
Dame Uta first expressed her views in an interview with the Times Educational Supplement in March. The NAS reacted to it in strong terms.
It wrote a blog post about "false narratives and outdated ideas", "misinformation" and "false claims".
Dame Uta says it's "just wrong" to dismiss her like this.
The NAS says anyone with an autism diagnosis will have been assessed against strict criteria and "have lifelong differences in communication, behaviours and focused interests compared to non-autistic people".
Dr Sue Smith, the NAS's head of clinical services, says: "We've got a group of people with a genuine need. We're having this weird debate about what they should be called."
She says this isn't just an academic row but has real implications for autistic people: "Historically a lot of people who weren't properly identified as autistic were given other really unhelpful labels", such as borderline personality disorder or bipolar.
She worries that re-labelling some autistic people could lead to them losing support.
Dr Monique Botha, an associate professor of psychology at Durham University, criticised Dame Uta's opinion using swear words.
Botha is autistic and stands by her reaction: "A lot of people were understandably upset and angry⦠I still am.
"Researchers have a duty to be a bit more blunt and upfront about how damaging these kinds of things can be."
Botha feels that Dame Uta's ideas add to a narrative that "there's some magical easy autism where you're just quirky, where everything in your life will eventually work out, and you're just using this as a crutch so that you can feel special, and it trivialises the reality of a whole bunch of people".
Botha says autistic people are united by key features: sensory sensitivity, a need for predictability, intense interests and struggles with communication.
"That doesn't mean that we will have the same lives or the same outcomes."
James Fitzpatrick was diagnosed in the 1990s, and doesn't speak. His father, Dr Michael Fitzpatrick, is a retired GP.
Michael says he's been shocked by the response to Dame Uta's stance: "Intolerant, strident, abusive discourse that's very redolent of the culture wars."
He feels some autistic people don't understand the reality for his family.
Michael says that James, now 34, has "never developed the capacity to engage with the world. That's the source of profound sadness to his family and a loss to himself."
"He would injure himself, bang his head on the floor, bite himself. If you tried to stop him, he would also bite you or scratch you or headbutt you. And as he got bigger, that became more of a problem."
James has calmed down with age but still can "attack you randomly for no apparent reason".
Michael can't see how the same diagnosis can hold true for James and for someone who lives independently - two "extremely different types of people".
Different challenges
Dr Rachel Moseley, an academic from Bournemouth University, was working in autism research when she was diagnosed in her late 20s.
She agrees that people like James are "incredibly neglected".
But she says: "There's room for all of us, we can still advocate for people with learning disabilities without saying that this group isn't valid."
She thinks ideas about dividing up the autistic spectrum lack nuance, especially around mental health.
"Every so often something will totally knock my feet out from under me," Moseley adds, saying she will self-harm and have suicidal thoughts.
"Everyone's challenges are different. But you can't make the assumption that the person with high support needs is always having a harder time. They will in some regards, but not in all."
To make her point, she cites studies that have found that while autistic people overall are more likely to take their own lives, these rates are highest in autistic people without learning disabilities.
Michael Fitzpatrick is unconvinced by this argument: "I seriously, seriously doubt whether the people with autism and no levels of learning disability have a similar level of pathology and life-threatening problems as the people with profound autism."
Lived experience
It's striking that both sides in this row accuse the other of lacking scientific rigour. One major flashpoint is around the study of masking.
This is when someone hides autistic behaviours to try to fit in with society. There's been an explosion of academic interest in this area.
Recently, a review found almost 400 research papers talking about masking, mostly focusing on autistic women who were diagnosed as adults and don't have any intellectual disabilities.
Dame Uta shudders when I mention the idea: "Agh! Such a vague notion." She dismisses some research papers on it as "absolutely poor quality".
Moseley says the exact opposite: "There is really high-quality work on masking, and it's startling and upsetting to see such work be denigrated."
She sees masking research as part of a "refreshing change" as autistic academics "bring lived experience into research".
But Dame Uta questions if autistic researchers can be neutral or if they have a conflict of interest.
She's something of an outlier with this view.
Professor Sir Simon Baron-Cohen is director of the Autism Research Centre at the University of Cambridge. When he started out, Dame Uta was his mentor. He disagrees with her on this.
He says: "Someone who's got a degree in molecular biology has one kind of expertise, but someone who's got lived experience has got another kind."
Overall though, Sir Simon says: "I'm not taking sides. I think the answer is to get both sides round the table. A lot of what seem to be irreconcilable differences are actually reconcilable."
He does think the term autism is too broad and can lead to "lumping together people who are so different".
His suggestion is to add sub groups. Type one could be autism with a learning disability. Type two could be autism with language needs. Other types could include conditions that can co-occur with autism, such as ADHD, depression and epilepsy.
He says: "Imagine, we could have dozens or hundreds of subtypes. Why put a limit on it? The more we have, the more precise we can be about what people need."
Once again, there is no consensus.
Dame Uta thinks subtypes could provide "a clean division between those who have these very severe needs and those who don't. But it can't go on endlessly."
The NAS is worried that breaking autism into smaller groups could lead to discrimination or the removal of support from people who need it. It says subtypes have "no clinical value, diagnostic relevance or practical application".
Sir Simon's answer is to "bring in autistic people so we can choose labels that they're comfortable with".
Moving goalposts
Kayleigh was diagnosed with autism in her thirties. She finds that people hold pre-conceived ideas about what autism is.
She explains: "Some will assume you can't spell your own name. Or you love trains. Or you're extremely clever. Or you're hyper focused on a boring hobby."
Since diagnosis she's been given various labels - Asperger's, high-functioning and AuDHD [Autistic with ADHD].
She says: "The goalposts keep moving. As an autistic person, I don't even know what I should be called."
For her, this row is a huge distraction from the real issues.
She's spent her life thinking she was "weird, sub-normal or really, really bad". She's angry that society didn't recognise that she was struggling.
Since diagnosis, she says she's had "zero" support from professionals. She says emotionally she feels she can only really go out if her family are with her. She's not been to her local town centre in years.
She wants more help, more understanding. She doesn't care what her condition is called.
She says: "You could call it 'silly brain disease'. I still know what I'm going through."
Additional reporting by Kris Bramwell
Lead image: Getty