Lawyers representing families of four people who died at Gosport War Memorial Hospital have written to the coroner to question the delay over the inquests into their deaths until after a major police probe, which could last four years.

Kent and Essex Serious Crime Directorate launched the investigation into the Hampshire unit after an inquiry found that hundreds of patients had their lives shortened through the use of opioids in the late 1990s.

A short hearing was held at Portsmouth Coroner’s Court last month to open inquests into the deaths of Dulcie Middleton, Horace Smith, Eva Page and Clifford Houghton, following requests from their families.

Coroner Christopher Wilkinson adjourned the hearings until the conclusion of the police investigation, which Hampshire police and crime commissioner Donna Jones has said could last up to four years.

A recent forum meeting was told police investigators had three million separate items to be scanned, stored and reviewed as part of “the most complex and significant investigation of its nature in the country”.

Emma Jones, partner at Leigh Day, who represents the families, said: “The families we represent have been waiting many years for a full account of the circumstances surrounding their deaths at Gosport War Memorial Hospital.

“To make them wait for another indeterminate length of time, when many of the families are themselves elderly, is not acceptable, and in any event is quite clearly unnecessary. We are asking the coroner to think again.”

Ms Jones said that inquests had previously been run in parallel with police investigations, including into deaths in the Hillsborough tragedy.

The new inquests will look at the death of 71-year-old Mr Houghton after he was admitted to the hospital in February 1994 for a period of respite.

He died on the day he was given two doses of diamorphine because of “deterioration”, and the 2018 review panel concluded that he was given opioids without appropriate clinical indication.

His stepdaughter Pamela Byrne believes there is reason to suspect her stepfather died a “violent or unnatural death”.

Mrs Middleton died aged 86 in September 2001, three months after she was admitted to the hospital for rehabilitation following a stroke.

Her nephew David Wilson and daughter Marjorie Bulbeck say Mrs Middleton’s treatment at the hospital was “neglectful and inhumane, she was not assisted with food and became dehydrated and was denied basic nursing care”.

Ms Page, 88, died in March 1998 and the Gosport Independent Panel report concluded her death was a case of opioid usage without appropriate clinical indication.

Mr Smith, 73, died in April 1999 after his condition had been said to be improving, although he was subsequently prescribed diamorphine.