Sir Ian Blair’s refusal to consider resigning after the fatal shooting of Jean Charles de Menezes was perhaps too brusquely expressed. The issue is not, as he suggested, the “level of support” that the Metropolitan Police continues to enjoy, but whether the police errors that led to the death of an innocent man, and the Met’s response to the terrible truth, make his position as commissioner untenable. When the concern aroused by this tragic incident has been heightened by glaring discrepancies between initial accounts and subsequent testimony, there must be no hint of bluffing it out.

Yet on substance, if not in tone, it is Sir Ian and not the dead man’s aggrieved cousin who is in the right. On the basis of what is known, there is no reason for Sir Ian to resign. The case made by the de Menezes family and others is that the police, after committing their fatal blunder, lied about what had happened; and that Sir Ian personally sought, in violation of established procedures, to block the mandatory inquiry into the incident by the Independent Police Complaints Commission. The precise timing of what was said and done is pertinent.

Sir Ian’s initial statement, within five hours of the Brazilian’s death on July 22, accurately linked the incident to the investigation into the failed London bombings of the day before, but then went on to add that “as I understand the situation”, Mr de Menezes had “refused to obey police instructions”.

He appears to have been wrong; but so, it turns out, were many eyewitness reports; to be wrong is not the same as a deliberate intention to mislead. To the contrary, it is clear from Sir Ian’s letter to the Home Office that same morning that he still believed that the police had been dealing with a terrorist suspect. His argument for a “review” of the IPPC’s role was that nothing should deflect from the counter-terrorist effort. He copied that letter to the IPPC — action hardly consistent with an attempted cover-up. Nor did the letter materially hold up proceedings; by that very evening, the Home Office had rejected his request and announced that the IPPC would investigate. After that point, the police not unreasonably insist, they could no longer issue public statements, even to correct accounts that they now knew had been erroneous.

It should not have taken the IPPC five more days to start work, and it should abandon holier-than-thou grandstanding about police delays, when far greater damage has been done by leaks of incomplete evidence from its own premises. The public has been left with a partial account of a botched police operation that, disturbingly, was conducted under a shoot-to-kill policy of which the public had not been told. Concerns range far wider than the case itself, to the entire conduct of counter-terrorism operations in this country. To protect the rights of possible defendants, IPPC reports cannot be published until they have been considered by the Crown prosecutors. It is all the more vital that the IPPC should finish its work in weeks, not months, clearing the way for an urgent and searching national debate.