Over a coffee, he tells me why the work his department, lately bolstered by two scientists from Haifa University, is so important.
'A big cause of autism is genetic and boys are more at risk'
"Understanding of autism is better than it was," says Baron-Cohen, 56. "I have been in the field for over 30 years. When I first started, people had not really heard of autism but now it is a household name."
He adds: "That does not mean it is completely free of stigma or that enough support is available."
At the age of 21, Baron-Cohen took his first job at the Family Tree school in Barnet, which was then one of the few specialist autism schools in the country. The school - which was run by June Felton, who has since made aliyah - employed six teachers for each of its six students. Classroom activities were filmed, so they could pinpoint the teaching methods that worked best for pupils.
"This was more than 30 years ago, when not much was known about the condition," he explains. "[Ms Felton] was trying to find educational methods almost from scratch, so it was a very exciting environment to work in.
"In those days, we thought autism was quite rare, whereas today we recognise it affects about one per cent of the population."
The experience motivated him to go back to university, where he completed his PhD.
Now, he is lobbying to receive more government funding for the Cambridge centre.
"If you have someone with a physical disability who is isolated, there would be an outcry. But, because someone who has autism or Asperger's syndrome looks normal, there is less urgency to do something about it.
"The health service is limited in terms of cash, but I continue lobbying."
He continues: "There are lots of frustrations. One stereotype is that autism is thought of as 'a male condition'. Actually, there are lots of girls and women out there who need a diagnosis.
"There is a lot of misunderstanding - even among the medical profession."
And Baron-Cohen, who in 2003 wrote a book on the differences between male and female brains, believes that scientists have a responsibility to battle sexism in society.
"I got into the psychology of sex differences because I wanted to understand why autism was more common in boys."
He has come to the conclusion that "sex differences are exaggerated, there is much more overlap.
"When I published that book, I spent a lot of space spelling out what I was not saying, rather than what I was saying.
"It is a field that is, quite rightly, controversial given the history of the inequality between the sexes in the workplace and society."
This year, a Danish study published in the Journal of the Royal Society of Medicine suggested that circumcision before the age of 5, could double a boy's risk of developing autism .
But Baron-Cohen is quick to dismiss the suggestion that Jewish men are more likely to suffer from autism.
"I have not seen that as a clear finding," he says. "I do not think the study was able to prove that there was a causal connection. It needs to be interpreted very cautiously."
Baron-Cohen explains: "A big cause of autism is genetic. We are studying why boys are more at risk - looking at testosterone pre-natally because the male foetus produces its own testosterone almost twice as much as the female foetus. The hormone changes brain development."
Professor Baron-Cohen remains as enthusiastic as ever in his work. He finds his professional subject "stimulating and interesting, that has not gone away," he says. "All these years later, I am still very excited by doing the research - that is what drives me.
"When the results come in, it is very exciting. I care about the patients, but I also care about the research being done." Now two Israeli post-doctoral researchers have joined his team with funding from British Friends of Haifa University (Baron-Cohen himself is a governor of Haifa University) in a concerted bid "to build bridges - a real link" between the two universities.
And he is not deterred by pressure from the anti-Israel academic boycott movement.
"To be perfectly honest, I just ignored it," he says. "I think it is wrong. I am sympathetic to the Palestinian perspective, but I think having a boycott towards Israel is painting the conflict as one-sided.
"I am very keen to see constructive ways to bring about peace. I do not think the academic boycott is a fair way to do it and I do not think it is going to be effective either."
Baron-Cohen, who grew up in Hampstead Garden Suburb, is nowadays a member of the Beth Shalom Reform Synagogue in Cambridge, and also attends the North Western Reform Synagogue in north-west London when he can with his father.
And there is no getting away from his famous cousin: Sacha: "I visit Sacha whenever I go to LA and he comes back to London quite a lot," he says. "We talk about what each other are up to - we are in touch all the time. But I'm sure, that is just like your family and your cousins.
"He is the one that has got the very big public profile - but he is not the only cousin."
