The care facility has been deemed “chaotic” and “unsafe” after 19-year-old Sophie committed suicide in May 2016.
The teenager, who suffered from bipolar affective disorder, social anxiety disorder and atypical autism, died two days later in Kingston Hospital as a result of her injuries.
Shortly before Ms Bennett died, the Care Quality Commission criticised the facility as inadequate in a number of areas – a rapid decline, as it had been rated good just six months earlier.
At an inquest, jurors were tasked with deciding whether changes at the facility run by charity Richmond Psychosocial Foundation International (RPFI) contributed to her death.
The home had seen a number of staff changes and was in the hands of interim manager Duncan Lawrence after the previous manager Vincent Hill resigned over fears of cuts to therapy.
West London Coroner’s Court heard Mr Lawrence did not have a legitimate medical doctorate, and had instead obtained a certificate from a “degree mill” in Denmark.
Mr Lawrence failed to attend the inquest despite being summonsed.
It also emerged that Ms Bennett had self-harmed in April 2016 and said she was experiencing suicidal thoughts, but staff at Lancaster Lodge had ignored advice to admit her straight to hospital for an assessment.
Instead, they decided to keep her in the home under close observation, but allowed her to close the bathroom door on the day she was found hanged.
CQC inspector Wynne Price-Rees found staff and patients were happy when he visited for a routine inspection in the previous September.
But he discovered “a totally different story” in March, adding: “I think it was chaotic.”
On the first day of the urgent four-day inspection, he said he found Mr Lawrence “disengaged” and lacking knowledge of essential care documents.
“He (Mr Lawrence) didn’t seem to have a grasp of the concepts that are fundamental,” Mr Price-Rees added.
The inspector said he had numerous concerns, including kitchen items not being locked away and poorly qualified junior staff.
In their conclusion on Thursday, the jury found that the changes to care, inadequately trained staff and the fact that staff were “in the deep end” and “learning on the job” all contributed to Ms Bennett’s death.
The jury found that a “grossly inadequate” observation plan was put in place for Ms Bennett, and not understood or followed.
They also said staff were not properly trained in carrying out room searches and did not know what items they should be looking for.
Ben Bennett, Ms Bennett’s father, also raised concerns about Elly Jansen, who was acting as a consultant to the RPFI board.
Mr Bennett described Ms Jansen as possessing an “extraordinary approach to management”, which was “like something out of the 19th century”.
It emerged that Ms Jansen was forced to step away from a psychiatric charity in the 1980s due to allegations of financial mismanagement and misappropriated funds.
Lawyers for the Bennett family allege that while not a trustee, Ms Jansen was effectively the “shadow director” of RPFI and “the controlling mind”, making decisions on staffing and management at Lancaster Lodge.
The inquest revealed several other residents at Lancaster Lodge became “very ill” amid the disruptions in 2016 and “at least one” attempted suicide .
Friend and fellow patient Clarissa Jeffrey said the changes in 2016 “made it feel like the residents were running the house”.
“The changes felt like they were fuelled by trying to … save money rather than trying to help the people in the lodge,” she said in a statement to the inquest.
Sophie told her mother Nickie Bennett the new regime saw the place become like a “boot camp” with strict rules and exercise, the court heard.
In a statement, Sophie’s family said: “We’ve waited nearly three years to find the truth about what happened to our beautiful daughter who, despite her many problems, had a fulfilling life ahead of her.
“We thank the jury for listening to the, at times, difficult evidence, and their clear conclusions which vindicate our concerns.”
The family said it hoped the CQC would pursue a criminal prosecution and criticised the Charity Commission for failing to attend the inquest.
“[The Charity Commission] has known about the issues surrounding the governance of RPFI since well before Sophie’s death.
“I hope that it will now apply the full force of its powers to take action against those trustees who have clearly been negligent in their responsibilities.”
On Friday, coroner John Taylor said he would now prepare a Prevention of Future Deaths (PFD) report to be submitted to the RPFI board, the CQC, Charity Commission and other interested parties to prevent future tragedies arising from poor care.