West London Mental Health Trust has accused a whistleblower of constructing “conspiracy theories” during an employment tribunal in which it faces bullying claims.

The former employee, psychologist Dr Hayley Dare, has alleged she was targeted with a threatening poison pen letter just weeks after raising concerns about a culture of poor practice within the forensic clinical unit at the trust.

The letter, as described in Dr Dare’s witness statement, urged her to withdraw her claims, warning her “you cannot beat us” and “how hard it will be on your children if you are unemployed”.

Dr Dare was also the target of alleged bullying by two of her bosses, causing her to suffer depression, anxiety and suicidal thoughts, Watford Employment Tribunal heard.

She has launched a case against the trust for detriment she claims she suffered as a result of her whistleblowing in early 2013.

The trust is the one of the largest in the country and is responsible for high security hospital Broadmoor as well as low secure units and local services.

Speaking of her whistleblowing, she told the tribunal: “I went to the chief executive to make some serious allegations against clinical staff and senior managers who had breached their duty of care in terms of patient care and staff welfare that could have led to a patient death.

“This was never about an individual; this was about poor patient care and bullying from a culture within the forensic clinical service unit.”

She added that the treatment she suffered was a direct result of the trust failing to investigate her claims properly.

Dr Dare was given nearly six months off work as a result of her distress but claimed the bullying continued after she returned and her work was undermined by colleagues.

But Ian Scott, representing the trust, accused Dr Dare of enjoying “conspiracy theories” and denied that her colleagues were in a “cohort” against her.

He added that the trust has provided her with support to help her return to her job.

Dr Dare started working for the Trust in 2000 and was appointed clinical head of the women’s forensic directorate in 2011.

The tribunal is due to give its ruling on November 10.