Those who hoped that Mr Campbell, the former director of communications in Downing Street, would be either apologetic over his part in the decision to take the UK into the lethal quagmire that is Iraq, or that he would admit to any doubt over the process, will have been disappointed.
Similarly, it was disappointing, though not unexpected, that the former spin-doctor did not admit that he had beefed up the government's now notorious dossier on Saddam Hussein's supposed weapons of mass destruction . Nor did he concede that, as many in the intelligence world believe, he took out the caveats and ambiguity.
Whatever the suspicions over his role at the time, and however unsatisfactory his evidence sounded, Mr Campbell also insisted that he did not override the intelligence judgment of the dossier's author, the chairman of the joint intelligence committee (JIC) Sir John Scarlett.
Earlier, Sir John told Chilcot that he did not believe he should alter Mr Blair's controversial foreword to the document which the then chairman of the JIC described as an "overtly political" statement. Yesterday, Mr Campbell rejected this, claiming that if Sir John's JIC had had concerns they could have raised them directly with the prime minister, an explanation that may be literally true but does not convey the real state of the relationship between a powerful Downing Street machine and its civil servants, even those in intelligence.
So, frustratingly for a public which still craves to know the real insider story of the war, there were few revelations or admissions from Mr Campbell. However, there was one piece of his evidence which is of significance: his statement that Gordon Brown, then the chancellor, was a key member of the inner circle consulted over the decision to go to war by Mr Blair.
During that period, Mr Brown said little or nothing on the conflict and there was speculation that he did not wish to be associated with the kind of militaristic adventure that would seem anathema to his Presbyterian and traditional Labour beliefs. Yet now we know that, from the start, Mr Brown was at the heart of the decision-making.
The political implications are hard to predict. The Tories, who supported the war, cannot exploit it at the general election so the main beneficiaries might be the Liberal Democrats who were, to their credit, were consistently against the Iraq invasion. So too can the SNP capitalise.
Conspiracy theorists may conclude that Mr Campbell was associating Mr Brown with the Iraq conflict to spread the responsibility and to scupper any attempt by Mr Brown to distance himself from the actions of his predecessor.
Whether this is the case or not, Mr Campbell has ensured that Labour will, for the second election in a row, face an electorate which can hold it to account for taking the country into what most now recognise was a disastrous war.