Professor Gary Ford, an expert in pharmacology at Newcastle University, was asked by Hampshire Constabulary during its investigation to look into five deaths – two of which were the subject of the inquests.

He claimed the levels of diamorphine administered through syringe drivers were 'reckless' and 'poor practice'.

In legal arguments, the families' lawyers called for the report to be included in evidence at the inquests but the coroner refused and instead relied on two other medical experts who had also prepared reports – of Professor David Black and Professor Andrew Wilcock.

Professor Ford examined the death of 74-year-old Robert Wilson, who was admitted to the Gosport War Memorial in 1998 after suffering from a broken arm.

Prof Ford noted: 'Mr Wilson was admitted for rehabilitation not terminal care.

'Following treatment Mr Wilson was noted to have had a rapid deterioration.

'The medical and nursing teams appear to have failed to consider that Mr Wilson's deterioration may have been due to the diamorphine infusion.

'In my opinion when Mr Wilson was unconscious the diamorphine infusion should have been reduced or discontinued.'

Prof Ford said the skills of nursing and non-consultant medical staff, 'particularly Dr Barton, were not adequate'.

In his conclusion he said: 'Routine use of opiate and sedative drug infusions without clear indications for their use would raise concerns that a culture of involuntary euthanasia existed on the ward.'

His findings were passed to Hampshire Constabulary, but no criminal prosecutions have ever been brought.

Families also say a second report – never before made public – should have been put before the jury.

Professor Richard Baker, pictured right, was commissioned by Sir Liam Donaldson, the then chief medical officer, to probe death rates at the hospital and the prescription of strong painkillers in 2002.

It followed a damning report by the then Commission for Health Improvement, which concluded that patients at the hospital were being put at risk. But the Baker report has never been made public and coroner Andrew Bradley refused to let it into evidence during the inquests.

Ian Wilson, son of Gosport War Memorial patient Robert Wilson, said: 'If they have got nothing to hide, if the government has got nothing to hide then release it and let us see it.'

Mr Wilson also hit out at the role of the coroner during the month-long inquests.

'I think the coroner was absolutely disgusting,' he said.

'He was totally biased towards the medical side. The way we were treated – it was like they wanted us all to go away quietly. But we're not going to go away. We are never going to go away.

'I will carry on now and make sure these people that are responsible for my dad's death are brought to justice.

'I think the police investigation we have had so far has been a complete cover-up from the very start.

'Hampshire Constabulary should hang their heads in shame. They did not investigate properly.

'They should do now.'

Bridget Reeves, the granddaughter of 88-year-old Elsie Devine, also accused the NHS of closing ranks to cover up what happened at the Bury Road hospital between 1996 and 1999.

She has now vowed to take their 10-year fight for justice on 'for as long as it takes'.

Ms Reeves added: 'The families' journeys are not over.

'Once we have all the evidence as denied by this coroner we will reflect on these last few weeks and decide our next steps.

'Extreme drug overdoses were given without justification or logic that rendered our relatives comatose in a matter of hours and dead soon after.

'To behave in this way should have consequences, but it seems that if you're on the NHS payroll you receive protection not prosecution.'

She said some medical experts had put their careers on the line 'to protect doctors like Dr Barton'.

She continued: 'The health service uses callous doctors like Jane Barton to relieve their bed-blocking issues and when families question mass overdoses and sudden deaths we hear nothing but lies from the professional bodies that are supposedly here to protect us.'

Her mother, Ann Reeves, added: 'I have always known it was a cover-up.

'I have spent 10 years of my life battling with everybody from the Ministry of Justice down to the Gosport MP Peter Viggers.'

She added: 'At the end of the day what I have heard today has just blown me away, and thanks to the jury for bringing me some justice at last.'