The Francis report shied away from explicit criticism of individuals involved in care failures at Mid Staffordshire Foundation Trust to avoid “perpetuating the illusion” that removing particular people would solve problems.

Robert Francis QC set out his approach to criticism at the beginning of his report, saying he recognised the “understandable human need” to identify people to blame.

He said the “main purpose” of the inquiry was to “identify lessons to be applied” and the purpose of identifying individual failures should be to “show examples of conduct or judgments to be avoided in future”.

He wrote: “In a system failure as widespread as that identified in this inquiry, it becomes a futile exercise to undertake; so many are in one sense accountable, it is far more effective to learn rather than to punish.

“To place too much emphasis on individual blame is to risk perpetuating the illusion that removal of particular individuals is all that is necessary. That is certainly not the case here.”

A number of senior figures, including NHS chief executive Sir David Nicholson, had roles at the strategic health authority or regulators responsible for the trust and were expected to be heavily criticised for taking so long to spot and act on evidence of appalling care.

In the days since the report’s publication there have been calls for the resignation of Sir David. He oversaw the trust as chief executive of Shropshire and Staffordshire SHA in 2005 and its successor organisation West Midlands SHA from the following year.

The prime minister and health secretary have both backed Sir David.

Last summer people due to be criticised in the report were notified in writing by the inquiry team and allowed to respond. An unanticipated level of challenge to the letters is widely understood to be behind the delay in the publication of the report from October 2012 to last week.

In the report Mr Francis blames the difficulty of sharing large extracts from the draft report with the letters’ recipients. This had the “unfortunate result” that some criticism appeared “more severe” in the warning letters than it was when viewed in context.