Coddington Court, near the Herefordshire market town of Ledbury, is a late-18th-century red brick mansion surrounded by farmland.

These days it goes by the name of Adhisthana, reflecting its reincarnation as the headquarters of one of the most influential Buddhist orders in the world, the Triratna Community, whose founder, Sangharakshita, lived there until his death last year at the age of 93. With its impressive grounds and gardens, it looks like a serene place for someone to spend their final years. But behind the scenes, the picture is a rather more turbulent one.

For decades the order has been dogged by claims of sexual misconduct, claims that often strayed into allegations of coercion and abuse but which were thought to involve only a handful of individuals at worst.

But now a bombshell internal report, produced by concerned members and shared with the Observer, has found that more than one in 10 of them claim to have experienced or observed sexual misconduct while in the order. Many of the allegations are against Sangharakshita himself, but others make it clear that he was not the only alleged perpetrator. Indeed, the report seems to indicate that the licentious culture the guru encouraged when he established his first centre in the 1960s, at a time when Timothy Leary was urging people to “turn on, tune in, drop out”, flourished across the order.

Yet, despite the lurid revelations, Sangharakshita’s influence lingers. The Adhisthana website carries many pictures of him, a bespectacled, slight man draped in holy robes. The photographs invite comparisons with Gandhi, but the two gurus come from very different backgrounds.

Born Dennis Lingwood, the son of a French polisher from Tooting, Sangharakshita, meaning “one who is protected by the spiritual community”, deserted from the British army in India during the second world war and wandered the subcontinent, studying with several leading Tibetan lamas.

Adhisthana (formerly Coddington Court) in Herefordshire is the headquarters of the Triratna Community.

Two decades on, he returned to London at the invitation of a group of Buddhists in Hampstead, with a mission to set up one of Britain’s first monasteries, before leaving for reasons that are disputed. Some claim that he was caught using rent boys, an allegation that the Triratna community said it had not heard before. At the time of his departure, the Hampstead group issued a statement that said: “Whatever may have been said to the detriment of his character in the course of recent speculation and gossip may now be withdrawn.”

Venturing out on his own, Lingwood developed his own, highly interpretative brand of Buddhism, drawing on elements of Nietzsche and Freud. Critics would accuse him of a pushing a “semi-intellectual potpourri of Buddhism” but he shrugged off the attacks, claiming he was helping the religion find new followers in the west.

Many of his ideas were unorthodox. Lingwood encouraged heterosexual followers to experiment with homosexuality as a means of expanding their minds; he was deeply critical of the nuclear family and of mixed-sex communities in general; he encouraged young men to break away from their families.

“I think the son has to cut free and maybe not have much to do with his parents for a year or two,” he once explained.

His thinking struck a chord.

“There was something anarchic and anti-establishment about it,” one man who has been a member since the late 80s told the Observer. “I’d seen the rows my parents had, how they’d tried to amass money and it hadn’t helped them. I decided that the nuclear family didn’t work for me. I didn’t want the get-married-get-a job narrative. I was looking for something different and what it offered helped me.”

Sangharakshita, born Dennis Lingwood, teaching at the Hampstead Buddhist Temple in 1966. Photograph: John Twine/Rex

As a growing number of predominantly young men flocked to Triratna, then called the Friends of the Western Buddhist Order (FWBO), it expanded dramatically. Today it has more than 30 centres in the UK alone and operates in 26 countries.

Thousands mourned Lingwood when his funeral was broadcast at Triratna centres around the world. His obituary in the Times suggested that he had arguably done “more than any other person to popularise Buddhism in the west”.

But fissures within the community he founded are now becoming major fault lines. An internal report by nine disaffected members, who call themselves the Interkula, makes troubling reading about the order’s historical safeguarding policies and the duty of care it had to its followers.

Its incendiary findings have hitherto gone unpublicised: a current member explained that it was not the Triratna way to share internal criticisms with the outside world. But they were drawn to the Observer’s attention by a former member who claims he was manipulated into having sex with Lingwood.

Of 423 respondents to a survey featured in the report, of whom two-thirds are order members and a quarter are “Mitras” – followers who may aspire to become order members – 55, around 13%, said that either they themselves, or someone they knew, had “experienced sexual misconduct by either Sangharakshita or other Triratna order members, in past and recent times”.

The report, which acknowledges that “some good progress” has been made in responding to the allegations, an approach the order describes as a “restorative process”, states: “While many respondents described misconduct between a more experienced male OM [order member] and less experienced male Mitra, as has been described many times in the past, other types of misconduct were also reported, including male order members becoming sexually involved with very vulnerable women … and inappropriate behaviour by a female order member.”

Some of the comments in the report are damning. One order member of more than 15 years said: “I know of several cases and the details are awful. They include alleged intervention on the part of one of the most high-profile OMs to try and encourage a victim not to testify to the police if questioned.”

Another said: “Yes, I know three OMs personally who experienced sexual misconduct by other OMs and have not been invited to participate in the restorative process.”

A third said: “I was sexually abused by older order members.”

A fourth added: “I know of four people who this describes. Only one of these was in the UK. I worry that this type of behaviour was much more widespread than generally believed.”

“I have friends who were sexually assaulted by senior OMs in recent times,” another said. “They reported it to other senior OMs. Nothing happened.”

It was not just men who were targeted.

“I know of a couple of women ‘friends of the movement’ who were pursued by male order members … both very vulnerable women – one ex-prison[er] pursued and one severe mental health problems – entered into sexual relationship with.”

Some of those who completed the survey questioned Triratna’s appetite for investigating the abuse.

“I think there is a large denial factor … I’m up for selling assets and making amends as part of us moving on and acknowledging our ignorance of the abuse,” one said.

If it came to that, and several law firms have floated the idea of bringing claims against Triratna, it would certainly have assets to sell. The latest accounts of its charitable arm, the Triratna Preceptors’ College Trust, reveal that in 2017, the most recent figures available, it alone was sitting on net assets worth more than £3.3m. It bought Adhisthana several years ago for a rumoured £5m.

But this is only part of the picture. The accounts explain that the trust acts as a hub for dozens of charities that operate in the UK and overseas. One member told the Observer that, in Cambridge alone, Triratna had eight or nine properties worth between £700,000 and £2m each. Another member suggested that its entire property empire was worth more than £100m.

It helps that the order is a charity and enjoys tax perks. And the fact that its members are often happy to work in its bookshops or cafes for very little helps keep its cost base low.

Today, much of the trust’s income comes from donations and organising spiritual retreats and meditation courses. Its position at the vanguard of the fashionable mindfulness movement was cemented four years ago when several of its leading members helped a cross-party group of MPs produce their influential Mindful Nation UK report, which extolled the benefits of the new psychological approach in treating mental health problems such as depression.

Mark Dunlop, now 69, was a victim at the Triratna Buddhist community. Photograph: Rosa Furneaux/The Observer

Mark Dunlop left the order in 1985 after many years working for it. A heterosexual man, he felt compelled to have sexual relations with Lingwood over a four-year period. “He didn’t have any charisma,” Dunlop said. “He was a slightly weird guy, in a way that worked in his favour because I thought: ‘I’m not being swayed by his charisma.’

“One theory about narcissists is that they have experienced some kind of trauma in their childhood so they don’t have any confidence in themselves, and they create this whole world as a compensation and manipulate other people to build up their own ego.

“That fits with how Lingwood behaved. He built up this fantasy of himself as a spiritual teacher, someone on a higher plane of understanding, but I always sensed he wasn’t a happy bunny. There was a sense of dissatisfaction lying underneath. I felt sorry for him, in a way. That’s one of the reasons I wanted to help him bring Buddhism to the west.”

It now seems that Lingwood’s behaviour provided a template that was copied by others who exploited the order’s hierarchy. Many who came to it seeking enlightenment aspired to become members. But this made them vulnerable to coercion by those in senior positions.

“There was a general feeling around at the time that you were ‘blocked’ if you had an aversion to gay sex,” one former member recalled in an online forum.

One Triratna retreat, in Norfolk, where Lingwood was resident for much of the 80s, was described by the member as “more reminiscent of a San Francisco gay bath-house than a Buddhist retreat”.

A current member told the Observer that in the early 90s a 17-year-old boy with obvious mental health problems ended up in a sexual relationship with an order member in his 40s when residing at a centre in the south-east.

Five years ago, an order member at another centre in London was caught exposing himself to a young child in a supermarket. After being found to have committed several similar offences, he was suspended indefinitely.

Misconduct has also been reported at centres overseas. One woman who attended an FWBO centre in New Zealand in the 90s said: “There was one ordained member when I was there who seemed to treat the centre as his own personal Tinder app, hooking up with one woman after another, using his position as guru to great advantage.”

Concerns were first raised about the order in a BBC news report in the early 90s, and then again in 1997 when the Guardian revealed sexual misconduct at one of its centres, in Croydon, south London. That exposé prompted the resignation of one member of the order.

In response to the Guardian’s report, one of the order’s senior members, Kulananda, wrote to the paper stressing that the abuse was confined to one centre and one individual. But in a blog posting 20 years later, Kulananda confirmed hehad been in a sexual relationship with Lingwood and that he had come to see that the guru’s behaviour towards others had engendered a “cultish-ness at the heart of things that, I believe, will ultimately be our downfall”.

The FWBO Files website contains a vast and growing repository of allegations from ex-members expressing similar views.

Towards the end of his life, Lingwood appears to have acknowledged the damage he had unleashed, expressing “deep regret for all the occasions on which I have hurt, harmed or upset fellow Buddhists”. But, even today, the order seems unwilling to confront its past head on: Triratna now describes Lingwood’s behaviour as “unskilful”, a key Buddhist term, but one which, to outsiders, seems to underplay the consequences of his predatory actions.

The order’s safeguarding officer, who goes by the spiritual name Munisha, insisted the order had learned lessons from past mistakes and said every Triratna centre in the UK now has a safeguarding officer.

“I’m extremely sorry if misconduct reported to any member of the order was not properly addressed at the time,” she said. “The Interkula’s survey includes accounts of misconduct which we would be keen to address. However, some of these are references to misconduct experienced by unnamed others, and we can only address a case where a named complainant is willing to tell us their story first hand.

“It is the policy of Triratna’s central safeguarding team that anything reported to us of a criminal – or even potentially criminal – nature is reported to the police, without exception.”

She confirmed that one of the order’s most senior members, Suvajra, who some had seen as a potential successor to Sangharakshita, had been “suspended in December 2018 after a rigorous internal disciplinary panel process found on a balance of probabilities that serious ethical misconduct had taken place.” She declined to explain the nature of the alleged misconduct.

Lingwood, of course, escaped such censure in his lifetime, enjoying the tranquillity of his final years cosseted away in the idyillic setting of Coddington Court, feted by his followers. Perhaps, though, in the twilight of his life, he anticipated that a higher judgment awaited him. His translation of a Buddhist text – Verses that Protect the Truth – was read out at his funeral.

One verse must have given him pause for thought: “Lead a righteous life, not one that is corrupt. The righteous live happily, both in this world and the next.”

Sangharakshita interviewed in 2009. Photograph: Vimeo

‘Leaving mother’: the group credo

Key extracts from Leaving Mother and Initiation into Manhood, a document written by a senior member of the Friends of the Western Buddhist Order in the 1970s and shared down the years within the order. The document reflects and helped shape the order’s thinking and confirms that much of Lingwood’s more controversial teachings were embraced and promoted by others.

“An initiation into manhood, then, is an experiential situation in which the false man dies in order that the true men may be born. The young man has to realise that he must submit and become totally passive to that which will liberate him from the domination of his mother.”

“Having abandoned the world of mother and all that it implies, the young man can now begin to realise that his assertiveness is natural to him and that it is no longer an act that he has to put on.”

“Many ‘mummy’s boys’ have a fear of passivity in a homosexual relationship even though that is what they may naturally want.”

“I would even go so far as to suggest that taking the passive role in a homosexual relationship could, for some men, constitute an initiation into manhood as (a) the man is surrendering his own pseudo-assertive side and therefore undergoing a sort of symbolic death, and (b) is experiencing his sexuality in a situation that is free from women and all their associations (ie, emotional dependency).”