A public inquiry into the scandal-hit Stafford Hospital is due to open later, years after campaigners first demanded an open hearing.
A 2009 report condemned conditions at the hospital, said to have caused hundreds of unnecessary deaths.
The last government ordered a private investigation, but refused a wider public inquiry.
But in June the coalition government said the families of those who died deserved to know what went wrong.
The problems at Stafford Hospital – run by the Mid Staffordshire NHS Trust – were first exposed by the NHS regulator in March 2009.
The Healthcare Commission said there had been hundreds more deaths than there should have been between 2005 and 2008.
Catalogue of failings
It listed a catalogue of failings, including cases where untrained A&E receptionists had assessed emergency cases.
The Labour government then launched several investigations.
“We deserve to know why it was allowed to happen, and whether it could happen anywhere else”
Julie Bailey, Cure the NHS
These included an independent inquiry, led by Robert Francis QC. However, this was held in private and did not have the power to compel witnesses to give evidence.
When it reported in February it said the trust had been driven by targets and cost-cutting.
Managers had been focused on winning elite foundation trust status during the problem years.
But campaigners said the failings went far wider than the hospital itself, and that the broader NHS and regulators should have realised there were problems and stepped in.
They demanded a full public inquiry with stronger legal powers.
In June, Health Secretary Andrew Lansley announced that Robert Francis would continue the work he had already done on investigating the hospital by leading just such an inquiry.
Mr Lansley said this would focus on how the culture in the NHS had allowed the failings to happen.
He said the families of patients who suffered at the hospital deserved to know that.
The inquiry will consider more than a million pages of evidence and will hear from dozens of witnesses.
Hoping for answers
Campaigners are hoping they will now get some of the answers they have been seeking for years.
They want to hear from the chief executive who was in charge at the time, as well as senior managers from the NHS in Staffordshire and Whitehall, and former health ministers.
Julie Bailey, who set up the campaign group Cure the NHS, said it was an important day for her.
“It means such a lot to us,” she said. “I hope this will lead to a big culture change in the NHS. We deserve to know why it was allowed to happen, and whether it could happen anywhere else.”
Stafford Hospital has been working hard to improve patient care over the last 18 months.
The new chief executive, Anthony Sumara, said they had taken on 140 more nurses, improved training, and changed procedures in the areas which had problems.
He welcomed the public inquiry and hoped it would help improve confidence in the hospital.
“It’s desperately important for the NHS in general that we get some answers,” he said.
He worries that the impending reorganisation of the NHS and a tougher financial climate could provide the ingredients for similar problems to be repeated.
“We need to make sure we don’t take our eye off the ball again,” he warned.
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