The inquiry aims to build on the work of an earlier independent investigation / Getty Images

A public inquiry into major failings at an NHS trust will "explore every relevant nook and cranny" in a bid to find out why appalling standards of care were allowed to continue, the lawyer leading the probe said today.

The inquiry into the care provided by Mid Staffordshire NHS Foundation Trust between 2005 and 2009 aims to build on the work of an earlier independent investigation which disclosed a catalogue of failings at the trust, which runs hospitals in Stafford and Cannock Chase.

Tom Kark QC, leading counsel to the inquiry, said: "The purpose of this second and now public inquiry is to focus not on what went wrong but how it was allowed to go on for so long without appropriate remedial action.

"Why did no one act to correct the serious errors that were undoubtedly taking place?

"Why did the healthcare system as a whole tolerate what were clearly unacceptable standards of care?

"Why did those who should have been in the right position to take steps not do so?"

He added: "Despite the existence of national and local agencies concerned with the regulation of the NHS and the delivery of primary, secondary and acute care services, the appalling lack of care was allowed to continue with little effective intervention.

"In leading the inquiry team I have sought to ensure that we explore every relevant nook and cranny of the health service.

"We as a team will do our utmost not to leave a pebble unturned which might reveal material of interest and relevance within the terms of reference."

The latest inquiry was opened in Stafford by Robert Francis QC, who will start hearing expert evidence next week.

Mr Francis also chaired the previous independent inquiry into failings at Stafford Hospital.

That inquiry, which published its findings last February, identified systemic failings at the hospital, where managers were preoccupied with cost-cutting and Government targets.

Launched after a Healthcare Commission report published last year, the previous inquiry found that appalling standards put patients at risk and between 400 and 1,200 more people died than would have been expected in a three-year period from 2005 to 2008.

The previous Labour government rejected calls for a full public inquiry into events at the hospital, instead ordering the independent inquiry.

Health Secretary Andrew Lansley said in June that the new inquiry would be held in public to combat "a culture of secrecy" and restore public confidence.

Mr Kark said the inquiry team had approached more than 170 individuals, organisations and agencies and written to 114 GP surgeries.

Mr Francis said: "We are all here because of the terrible standard of service inflicted on so many of the patients who went to Stafford Hospital and their families.

"Last year, in my first inquiry, I sat and listened to many stories of appalling care.

"As I did so, the questions that went constantly through my mind were, why did none of the many organisations charged with the supervision and regulation of our hospitals detect that something so serious was going on, and why was nothing done about it?

"That question was one which many patients and their families and, it is fair to say, healthcare professionals as well, wanted to be answered."

He added: "While we are not here to reinvestigate what went wrong in Stafford Hospital, I think it is important ... that we keep at the forefront of our minds the terrible effect of the system's failings on those it was meant to serve."

Mr Francis said the main purpose of the inquiry was to find out why no action was taken by NHS management before the intervention of the Healthcare Commission, and to identify what lessons could be learned.