The Leveson inquiry into the UK print media has taken an unusual turn with the revelation that one of the centrepieces of the whole phone-hacking affair — the wiping of messages from murdered teenager Milly Dowler’s phone — was almost certainly not done by News of the World employees, as had been alleged.

The allegations concerning NotW journalists, and private detective Glenn Mulcaire, were made by Guardian journalist Nick Davies, as part of the long investigation of the phone-hacking affair. The suggestion that repeated hacking of Milly Dowler’s voicemail had deleted two old messages, and thus given her parents hope that she might be alive, was the catalyst for a whole chain of events — a grovelling apology by Rupert Murdoch, and the negotiation of a huge out-of-court settlement with the Dowlers, and the closure of News Corporation’s News of the World, the UK’s biggest-selling newspaper.

But the Leveson inquiry has now been informed that the voice messages on the phone were probably automatically deleted. Neil Garnham, QC, a lawyer for the Metropolitan Police, has told the inquiry that the system used by the phone provider in question automatically deletes messages after 72 hours, and that this was the most likely cause of the deletion.

The Guardian has since appended a footnote to its original story on its website to this effect, and Davies has written a piece claiming that the vast bulk of the paper’s reporting on this specific matter has been vindicated. Davies argues that the original story was accurate in terms of what the police knew at the time — which, given police behaviour throughout the hacking affair, appears to be curiously trusting of the plod.

Nor does it answer a key question — why didn’t The Guardian make any checks to see if it were possible that the voice messages had been deleted automatically? There are only five phone providers in the UK. Even if the Dowlers hadn’t known what provider their daughter had used, wouldn’t it have been straightforward, and duly diligent, to establish that automatic deletion wasn’t possible?

Lord Leveson is taking no chances on the matter, since everything remains unclear — he’s established an independent sub-inquiry into the whole Dowler affair, to sort out what really went wrong. Davies and The Guardian have made the point that no one else raised the question as to whether News Corp activity had deleted the messages, but — well, why would they?

It had been comprehensively established that News Corp had imposed no moral boundary as to when hacking should be performed, and any News Corp cavilling would have looked liked special pleading, and hardly mitigated its guilt. The police, for their part, were hardly likely to question their own, much-maligned investigation. It fell to the paper doing the original inquiries to make sure they had their story straight.

The Guardian’s account of the tangle has been met with less than total agreement. In The Independent, Stephen Glover has accused the paper of burying a correction of the “most important story it has ever published, one that closed the News of the World“. Glover argues that the most recent claim by The Guardian — that NotW journalists “probably were responsible for deleting some of the missing girl’s messages” was purely speculative and a long way from its earlier claims.

Nick Davies has blamed executives and editors at The Guardian for “pecking at” the clarification of the original story, and leaving it deliberately vague.

The Leveson inquiry continues.