There have to date been two separate inquiries into the wherefores of Britain's participation in the Iraq war - those of Lords Hutton and Butler in 2004.
Each of these supplied voluminous material for public consumption but, while masquerading according to public expectation as quasi "trials", their remits were simply to ascertain the facts.
It was not to apportion blame, although, when the conclusion was reached that this hugely unpopular war was largely an accident of history, and that no single individual or group of individuals was at fault, there were howls of outrage and cries of "whitewash".
It is in response to the unsatisfactory aftermath of the former that the Chilcot Inquiry into the Iraq war was conceived, and set in motion last week.
Whether any more definitive conclusions, particularly with respect to culpability, will emerge from this inquiry must be open to doubt, a fact noted by commentators on what has become "the biggest show in town" even before it is a week old.
The Chilcot Inquiry, wrote Guardian columnist Simon Jenkins, "can no more deliver accountability than could its predecessors".
The questions the inquiry might seek to answer, however, are what assurances did former British prime minister Tony Blair give to former president George W.
Bush on Britain's participation or otherwise in the war, and when; was "regime change" considered legal and was Mr Blair advised over this; did the intelligence agencies allow their information to be misconstrued as the case for war was made; and what significant plans, if any, were made for Iraq post-invasion?
In the first few days, while there was much talk of "ground-breaking" revelations, most of these simply confirm information already in the public domain.
As Mr Jenkins has robustly remarked in print, the report could be written in one sentence: "Tony Blair went to war in Iraq because he lacked the guts to stand up to George Bush, say the invasion was not justified by facts or law, and refuse to join him in Baghdad."
And a number of senior legal figures have queried Sir John's ambition that the inquiry would seek to establish the legality or otherwise of the war, and Britain's participation in it, primarily because the panel of six hearing the evidence and testimony has not one legal expert or senior lawyer among them.
Notwithstanding that many matters have been established either through leaked reports, published memoirs or loose tongues, the fact that Mr Blair's government, or at least Mr Blair himself, had decided up to a year before the invasion that it was a "complete waste of time" to resist the US drive for regime change in Iraq, arrives with a certain frisson.
This was part of the picture given by Sir Christopher Meyer, British ambassador to Washington from 1997-2003, to the inquiry.
He also confirmed that the eventual invasion in March 2003 was dictated by the "unforgiving nature" of the US military build-up, rather than by the failure of diplomacy or UN weapons inspections which simply had not been given time to do their job.
That left British officials "scrabbling for the smoking gun", namely the much talked about evidence of Iraqi weapons of mass destruction as a pretext for the war as preparations continued and the case for invasion was made in Westminster.
He went on to say that "we - the Americans and the British - have never really recovered from that, because, of course, there was no smoking gun"; and to imply that Mr Blair failed to leverage advances on the Palestinian/Israeli problem or demand better post-invasion planning for Iraq in return for the eventual support of Mr Bush.
With blanket coverage in the United Kingdom press, the Chilcot show looks set to run and run.
Exactly where it will lead to and what will result, however, remains unclear.
As Sir John himself has said, his inquiry is not a court and neither does it exist to apportion blame.
And, as others have pointed out, while certain individuals, such as Mr Blair, may certainly feel the heat, the British Parliament itself sanctioned the war and, whatever the inquiry reveals, bears a high degree of culpability itself.
Others still have declared it an outrage that the Chilcot report will not be ready and released until after the next British general election, which means in the unlikely event of it leading to a pandemic of finger-pointing it will have little impact on the make-up of the new body of elected politicians, many of whom will have voted for participation in what is increasingly regarded as a capitulation to US power and a tragic and needless war.