At least 450 people had their lives cut short by the administration of opioids at Gosport War Memorial Hospital between 1989 and 2000, a damning investigation has found.
The "institutionalised regime" of prescribing the drugs without medical justification "followed a clear pattern over time", and continued despite concerns being raised by nurses between 1991 and 1992, the report shows.
The £13 million investigation, first launched in 2014, found a number of organisations including the hospital management, the department of health and Hampshire Police "all failed to act in ways that would have better protected patients and relatives".
The Gosport Independent Panel was led by the former bishop of Liverpool, the Rt Rev James Jones, who previously chaired the Hillsborough Independent Panel.
The reports states there was "a disregard for human life" at the hospital.
The panel said it was not its job to call for criminal charges, but called on the health secretary, home secretary, Attorney General and Hampshire Police to "recognise the significance" of the report, and "act accordingly".
A statement from the families of victims said: "Our vulnerable relatives, who were stripped of their final words to their loved ones, silenced by overdoses, is more than catastrophic."
This sort of behaviour going on in our NHS is both chilling and precarious. As victims of crime we are all entitled to have an explanation when an alleged injustice has occurred. But this has been sinister, calculated, and those implicated must now face the full rigour of the criminal justice system.
How many people had their lives shortened?
Between 1989 and 2000, the records examined by the Gosport Independent Panel showed 456 patients had their lives shortened through the medically unjustified administration of opioids.
But the report adds at least another 200 patients "probably" also had their lives cut short, when missing records are taken into account.
Who was responsible for the prescribing and administration of opioids?
The panel found that, over a 12-year period as clinical assistant, Dr Jane Barton was "responsible for the practice of prescribing which prevailed on the wards".
In 2010, the General Medical Counci ruled that Dr Barton, who has since retired, was guilty of multiple instances of professional misconduct relating to 12 patients who died at the hospital.
She was never struck off.
Nurses on the ward were not responsible for the practice but did administer the drugs, including via syringe drivers, and failed to challenge prescribing, the panel said.
A number of nurses did however raise concerns between 1991 and 1992, but their warning went unheeded.
Consultants, though not directly involved in treating patients on the ward, "were aware" of how drugs were administered but "did not intervene to stop the practice".
Why has it taken so long for the scandal to come to light?
When relatives complained or raised concerns, they were "consistently let down by those in authority - both individuals and institutions", the report states.
Hospital management, Hampshire Police, the Crown Prosecution Service (CPS), General Medical Council (GMC) and Nursing and Midwifery Council (NMC) "all failed to act in ways that would have better protected patients and relatives", it said.
From 1998 a number of organisations had knowledge of "at least part of the picture" of what was going on at the hospital, but failed to identify the underlying nature of the problem or deal with it effectively.
Damningly, the report says each of these organisations "may have acted in its own interests and those of its leaders, motivated by reputation management, career self-preservation and taking the path of least resistance".
The report also details how the police investigations were limited in their depth and in the range of possible offences pursued.
What has been the reaction to the report?
Liberal Democract MP Norman Lamb, who announced the launch of the inquiry as care minister in 2014 said the findings were "shocking and devastating in equal measure" not just due to the number of patients affected by "also the disgraceful closing of ranks to stop families from getting to the truth".
Theresa May has described events at the hospital as "deeply troubling" and apologised to families over the time it took to get answers from the NHS.
Health secretary Jeremy Hunt said "any further action by the relevant criminal justice and health authorities must be thorough, transparent and independent", and suggested that Hampshire Constabulary should consider whether another force should be brought in.
Hampshire Police said it carried out three detailed investigations between 1998 and 2006, and the evidential test for prosecution was not met at the time.
It will "assess any new information" in the report, before deciding on the next steps.
Janet Davies, chief executive of the Royal College of Nursing, said "the report makes for very sober reading" adding: "Nursing as a profession must work hard to seek out lessons from Gosport and we expect that approach to be shared by regulators and the health and care system.
"The report is right to praise the bravery shown by the nurses who raised concerns. It highlights how difficult it can be for nursing staff to challenge the decisions taken by others."
Charlie Massey, chief executive of the General Medical Council, said: "We are committed to taking any further action necessary in light of information revealed by this report."
Timeline of events in the Gosport War Memorial Hospital scandal
August 1998 - Gladys Richards dies in Gosport War Memorial Hospital after going in for rehab following a hip operation. Her family report concerns about her treatment to the police and the coroner.
2001 - In the three years after Mrs Richards' family came forward, three more went to police and two more case were reported to the NHS ombudsman.
July 2002 - The Commission for Health Improvement (CHI) criticised Portsmouth Healthcare NHS Trust, which ran the hospital, for excessive use of pain relief and sedative drugs.
February 2005 - Hampshire Police detectives pass files of evidence to the Crown Prosecution Service (CPS) about the deaths of elderly patients.
December 2006 - Hampshire Police announces no-one would face prosecution over the deaths after a four-year inquiry. The CPS says that negligence could not be proven to a criminal standard and that there was no realistic prospect of conviction of healthcare staff.
April 2009 - An inquest jury rules drugs given to five elderly people at the hospital contributed to their deaths.
January 2010 - The General Medical Council finds Dr Jane Barton guilty of serious professional misconduct. A panel found she made a catalogue of failings, including issuing drugs which were "excessive, inappropriate and potentially hazardous". She was not struck off.
March - Dr Barton retires from medical practice.
August - The CPS announces no criminal charges will be brought against Dr Barton after finding insufficient evidence to mount a prosecution for gross negligence manslaughter in 10 key cases.
April 2013 - A coroner rules that medication given to Mrs Richards contributed "more than insignificantly" to her death.
July 2014 - An independent investigation into more than 90 deaths at the hospital is launched by health minister Norman Lamb.
June 20 2018 - The inquiry is published.
An earlier separate review into deaths at the hospital, led by Professor Richard Baker, found "almost routine use of opiates" for elderly patients had "almost certainly shortened the lives of some".
It could not be published in full until 2013, 10 years after it was completed, while inquests were held and due to a police investigation.