The CQC said when it was alerted to the case it followed up directly with the supplier to understand the circumstances surrounding Liam’s death and whether further regulatory action might be necessary.

Karen Knapton, of the CQC, said: “Of the ten inspections of St Mary’s Hospital that have been carried out since 2016, the CQC has taken enforcement action in six, including issuing warning notices.

“CQC regulatory action helps drive improvements and ensures people receive safe care.

“The service in the last inspection was rated as good.”

Elysium Healthcare said that in the three years since Liam’s death “detailed action plans have been fully integrated to address the issues highlighted during the investigation”.

This is something Mr McGenity disputes.

“We have patients and people who tell us it hasn’t changed,” he said.

“That makes me very angry. There are vulnerable people who are not getting the improvements and the lessons learned to prevent it from happening again.”

He said he was determined to help other patients, adding: “If we could do something to save a life it would be fantastic if we could make changes to help others more than that it would be just fantastic.”

The Department of Health and Social Care said a “healthy” NHS required “strong regulation” and that it was reforming the CQC to ensure it was “fit for purpose”.

He said the mental health system was “outdated” and was “letting down some of the most vulnerable people in our society”.

A spokeswoman added: “We are adapting the Mental Health Act to the 21st century, so that patients are treated with dignity and respect, and the public are kept safe.”