He was named after the velvet-voiced Hollywood actor Ronald Colman, a prophetic choice for a future psychiatrist to the stars, who treated Sean Connery for James Bond-stress in the early Sixties by introducing him to the hippies' favourite psychedelic drop-out drug, LSD. Arguments have raged ever since over whether Ronald David Laing's radical methods made him a true shaman – a discoverer of profound truths about the human psyche – or just a very clever showman with good PR.

The Beatles, Jim Morrison of The Doors and the poets Sylvia Plath and Ted Hughes all worshipped at the celebrity court of this charismatic high priest of Sixties counter-culture, the so-called “acid Marxist” considered by some to be a less wacky British version of America's anti-Establishment, acid-head psychologist, Dr Timothy Leary. First published in 1960, RD Laing's seminal work, The Divided Self: An Existential Study in Sanity and Madness, was written when he was just 28 years old; it became a best-seller and earned him a global reputation. Yet nearly three decades later, in a 1989 Channel 4 documentary transmitted the year he died, Laing wryly remarked of his own legacy: “I feel I'm regarded [by my psychiatric colleagues] as a brilliant man who is pretty disturbed.”

A man who challenged medical orthodoxy as much as he did was always going to make enemies within the Establishment. Laing argued that the old Bedlam-based system of incarcerating people with mental illnesses and treating them with anti-psychotic drugs and inhumane electric-shock treatment had contributed to people's psychological and emotional distress and was therefore part of the problem. With his beliefs in the power of self-healing, he became an important part of the anti-asylum movement, which worked towards the community-care model that is the norm today – a process first advocated in 1962 by the then Tory health minister Enoch Powell (for mainly economic reasons).

His boldest experiment was the idealistic concept of the “safe haven” for mental-health patients, without locks or any anti-psychotic drugs, that he and fellow founders of the UK mental-health charity, The Philadelphia Association, set up at Kingsley Hall 50 years ago in Bromley-by-Bow in London's East End. The association, which continues today, was set up to challenge accepted ways of understanding and treating mental and emotional suffering; key to that was, and still is, a commitment to conversation as a way of articulating what disturbs people.

Oscar Pearce and Alan Cox (above) in 'The Divided Laing', a black comedy premiering at the Arcola Theatre in London (Adam Bennett)

To mark that 50th anniversary, a new jet-black comedy, Patrick Marmion's The Divided Laing, or The Two Ronnies, is now premiering at the Arcola Theatre, starring Alan Cox as Laing in a production by the mental-health theatre group, Stepping Out Theatre. Meanwhile, David Tennant has signed to play Laing in a new feature film to be shot next year, Metanoia, by a Laing biographer, the film-maker Robert Mullan, with co-stars Elizabeth Moss from Mad Men, Michael Gambon and Gabriel Byrne. Tennant claims to have “long been fascinated” by Laing's life and work“, while another celebrity fan is the author Hilary Mantel, who states on the official RD Laing website that ”it is time to look freshly at a brilliant pioneer whose work has been widely, perhaps deliberately, misunderstood“.

Part of the problem with Laing's complex legacy, according to his son and biographer, Adrian Laing, was that his most famous theories, which were about the influence of family and society on mental health, were often misquoted and misinterpreted to sound like the psychiatric equivalent of Philip Larkin's baleful poem about parents (“They f*** you up, your mum and dad”). “Dad didn't say that families always cause madness: he told me towards the end of his life that some people are born mad, some achieve madness and some have it thrust upon them,” Adrian tells me. And Laing revealed a refreshing common sense in the aforementioned Channel 4 television documentary when discussing his cognitive behaviour therapy techniques, a talking therapy that steered people away from negative thoughts and encouraged them towards positivity. One of his patients was suffering from a feeling of catatonic immobility that meant she could hardly walk along the street, so Laing suggested to her that she might “market” her condition by becoming an artist's model – a crafty solution that broke the spell and restored her to full movement. In RD Laing's world, a grounding sense of humour was never too far away.

However, his striking ability to think outside the conventional box in trying to revolutionise the treatment of psychosis and schizophrenia inevitably became overshadowed by a hedonistic lifestyle that led to alcoholism in later life, with Laing finally removed from the GMC's medical register of practitioners two years before his death. His fondness for Eastern-influenced rebirthing techniques was regarded by many as crank therapy. Yet although the Sixties often takes a bad rap for the naivety of its excesses, does Laing really deserve to be thrown out with the bathwater?

The only child of a Scottish Army engineer, David Laing, and his wife, Amelia, Laing studied medicine at Glasgow University and first became interested in mental-health issues during his National Service in an Army psychiatric unit, before joining the Glasgow Royal Mental Hospital as the youngest consultant in the country. After moving to London and working at well-known institutions such as the Tavistock Clinic, he cut loose and went on to establish Kingsley Hall as a commune where patients and psychiatrists lived together in a system that treated patients as people to be talked to and empathised with, not objects to be medicated. This anti-asylum ran for five years, made notorious by such cases as a schizophrenic called Mary Barnes who was later immortalised in the 1979 play Mary Barnes by David Edgar. At Kingsley Hall, Barnes underwent regression therapy back to her infancy and painted the walls with her faeces until she was given paint instead by Laing's resident psychiatrist colleague, Joseph Berke, and discovered a talent for art, later becoming a successful painter after her recovery and co-founding the Arbours Housing Association for people with mental-health difficulties.

In the Sixties spirit of “letting it all hang out”, the place became a magnet for thrill-seekers and party animals. According to a former patient Francis Gillet, Laing would keep LSD (not outlawed in the UK till 1966) in the fridge as a “sort of spiritual laxative”. Yet he was hardly the first to do so: LSD had been a fashionable therapeutic treatment since the 1950s, especially in the US, where its hallucinogenic properties were used to simulate madness temporarily for the purpose of scientific study to unlock the mysteries of the brain.

Gillet also recalled Connery, one of Laing's celebrity friends, coming to a Kingsley Hall party one night for some Scottish bonding – a bout of Indian wrestling – with Laing in the games room to “see which Scotsman was tougher, James Bond or Ronnie Laing”. The moment when Connery was persuaded by Laing to drop a tab of acid with him in 1964 to relieve the stress of making Goldfinger was initially alleged in his first wife Diane Cilento's autobiography, 2006's My Nine Lives, when she wrote that the actor had to go to bed for several days to recover. The allegation, which Connery has never commented on, was repeated in Edna O'Brien's 2012 memoir A Country Girl, when she recalled how Connery had advised her back in 1970 not to take the drug because his bad trip with Laing had carried “a freight of terrors”.

Needless to say, the immersive Kingsley Hall experience demanded total dedication, which took its toll on family – or in Laing's case, his families. He fathered a total of six sons and four daughters by four women, with Adrian (by his first wife, Anne) later quoted as saying: “It was ironic that my father became well known as a family psychiatrist when in the meantime he had nothing to do with his first family.” When I talk to Adrian, he explains: “Me and my sisters and brother felt like the abandoned ones because Dad had a new, second family – out of sight, out of mind. But by the time I was a teenager, when my brother and I went to stay with him in 1973, I started to have a relationship with dad independent of my mother. Fundamentally, dad was about choice and consent and behaving in a way that is going to make your mind and life better and not postponing that by getting sidetracked into medication. But by the same token there was a very radical, wild side to him. By the 1980s, around the time of the final split of his second marriage, he did succumb to heavy drinking. And that, to me, was always the dividing line between what sort of dad I was going to encounter: the sober dad or the drunken, raging dad. When sober, he was on good form: articulate, calm and clear-minded...

He was a creature of his time, when every psychiatry student had a paperback copy of The Divided Self in their back pocket,“ says consultant psychiatrist Dr Isidora Ranjit-Singh. And the Sixties were all about experiment, a venture into the unknown, even though as Jonathon Green's 1988 book Days In The Life; Voices From The English Underground 1961-1971 points out: ”The alternative society was largely a middle-class phenomenon.“ One admirer from that time, a former film student, David Gale, who is now a playwright and university lecturer on theatre, recalls how he and his friends, some of whom were members of the Philadelphia Association, saw Laing as ”the Elvis of the psyche; we regarded his books on psychiatry as the equivalent of Jack Kerouac's On The Road, a journey to self-awareness“. Today, however, the so-called revolution has turned out to be a capitalist one, with that counterculture now commodified in everything from yoga classes at every high-street gym to classic Sixties songs turned into television commercial jingles.

As The Divided Laing playwright, Patrick Marmion, wistfully puts it: “The great thing about the Sixties was the idea that the world could be otherwise. Capitalism has such a pervasive grip on people's thinking now, but in the Sixties there was more openness, a more mystical way of thinking that has now been commodified into leisure and lifestyle – a decaffeinated and unleaded version of that vision. We are so relentlessly solution-oriented now. One of the most pertinent lines from The Divided Self is, 'I'm not an object to be changed, I'm a person to be accepted'.” All of which recalls Patrick McGoohan in that Kafkaesque television fantasy series The Prisoner, saying: “I'm not a number, I'm a free man!”

Laing's inspirational influence lives on, not least in the more compassionate way we treat mental-health problems these days – especially in recognising depression, which he himself suffered from at times, as a serious illness. Such has been the lasting influence of a book that sought to demystify madness that The Divided Self is still read as part of A-level psychology courses and as an existentialism model in universities. And the Philadelphia Association continues to offer training, affordable therapy and two community houses for those seeking retreat.

Another Laing admirer – though with reservations – is Professor Anthony David, vice-dean of the Institute of Psychiatry, Psychology and Neuroscience at King's College London and consultant at the Maudsley Hospital NHS Trust, who also wrote the foreword to the Penguin Modern Classics edition of The Divided Self. “He grew up and was educated in the Forties and Fifties, when the number of people in asylums in the UK was at its height,” David says. “While most of the country was content to ignore these people, Laing put the spotlight on them and showed it was possible to enter into an empathetic understanding with them; he argued powerfully for barriers between patients and the professionals, doctors and nurses, to be torn down – and this is now taken for granted. What naturally flowed from this was a critical stance towards the psychiatric profession, which, for Laing, was at its core dehumanising and oppressive.

“[Yet] the profession, while sometimes prone to fads and fashion, is above all a branch of medicine and takes seriously well-conducted empirical research – which was not Laing's forte. Where his influence is viewed most negatively is his work with people with schizophrenia, which appeared to blame parents for their children's illness and which discounted other physical, genetic, social and psychological factors. Later in his writings, he broadened his critique to the whole of medicine and other political structures and again, to some, seemed to romanticise mental disorder. This work now seems very much of its time in the Swinging Sixties – but in my view, his earlier work still has lessons for us today.”

Although she also values Laing's pioneering work in talking to patients, Dr Ranjit-Singh is critical of his lasting legacy. “Although community care is the norm now, I think it has some disadvantages in that it leaves people quite isolated,” she argues. A consultant psychiatrist at the Central and North West London Mental Health Foundation Trust, she works in the emerging field of early intervention in psychosis, with an ethnically diverse population in Brent. She believes Laing became a kind of hostage to his own propaganda about a dysfunctional society sometimes causing madness. “His major failing is that he underplayed the role of the medical model – that psychosis can be related to genetics, the chemistry of the brain, and that medication particularly can help to correct some of the defects – in order to prove his social theory that parents can influence the development of psychosis by creating conflict,” she says. “I think he was both empathic and radical in his thinking; I suspect he used alcohol and drugs to try and encounter his own 'madness'. But I don't think he was truly mad, just quite hedonistic.”

Ranjit-Singh believes that Laing's “failed experiment was all part of that optimism of the Sixties. Non-treatment can have catastrophic consequences. Having said that, Laing had a limited choice of drugs to prescribe in those days: just Largactil (chlorpromazine) or lithium, both of which have a lot of side-effects, not the gold-standard clozapine that we prescribe today. But in my view, he didn't understand the interaction between illicit substances such as LSD and cannabis and mental health: illicit drugs are a contributory factor in psychosis. LSD is an awful drug that can result in seemingly psychotic flashbacks which can continue after the patient has stopped using it. The good thing is that LSD is not used very much these days: the real problem we have instead is the increasing use of strong cannabis, such as skunk weed, which can cause very severe psychotic reactions”.

Laing's anti-asylum at Kingsley Hall continued for five years until two people jumped off the roof and made the place notorious bringing the experiment to an end in 1970. As for Ronnie Laing's end, he died as he had lived – in a counterintuitively controversial way from a heart attack after going on the wagon. He was on a tennis court in St Tropez at the time. “Far from dying of hedonism, dad sort of died of sobriety,” Adrian Laing says. “He was a traditional alcoholic in the sense that he could only oscillate between abstinence or excess, nothing in between. His body had become dependent on alcohol, so giving it up was a reckless thing to do – and the absence of drink killed him.” It seems like an appropriately all-or-nothing way to go for the celebrity psychiatrist who so divided people's opinions.