It is a measure of how weak Andrew Mitchell's position is that David Cameron couldn't summon a word in defence of his Chief Whip at today's PMQs. Challenged by Ed Miliband to say whether Mitchell (who sat visibly trembling on the frontbench) used the words attributed to him by the police ("fucking plebs"), Cameron merely reiterated that the Chief Whip had apologised and that his apology had been accepted. He said nothing to suggest that Mitchell is secure in his post, simply stating that the government "will get on with the big issues". The Chief Whip didn't help matters by shouting "I didn't" when Miliband claimed that he swore at the police, inviting the press to again ask what he did say.

Miliband, who had earlier referenced Boris Johnson's call for those who swear at the police to be arrested, quipped: "It's a night in the cell for the yobs, it's a night at the Carlton Club for the Chief Whip". He later added: "They say that I practice class war and they go round calling people 'plebs'." But the Labour leader slipped up when he claimed that "everyone else is losing their jobs, the Chief Whip is keeping his". Given today's positive employment figures (which Miliband noted earlier in the session), it wasn't the best attack line to use and Cameron was swift to capitalise. "He wrote those questions yesterday before unemployment fell," the PM observed. Miliband also again falsely implied that all millionaires will benefit from the abolition of the 50p tax rate (he should have said those who earn £1m a year), a line that gives the media a licence to probe his own personal worth.

The session ended rowdily with Cameron baldly refusing to answer Labour MP Chris Bryant's question on why he had not released all of the text messages between himself and Rebekah Brooks. Cameron insisted that this was because Bryant had refused to apologise for previously quoting unpublished material from the Leveson inquiry (some of which had contained untrue claims about him), but it made him look like a man with something to hide.

Update: Tory vice chairman Michael Fabricant, who resigned as a government whip in last month's reshuffle, has taken to Twitter to confirm that Mitchell did intervene during PMQs to claim that he "didn't" swear at the police.

Several MPs have confirmed to me that AM did indeed say #pmqs "I didn't swear" (at the police). This puts a whole new light on the issue.

— Michael Fabricant (@Mike_Fabricant) October 17, 2012

As I wrote above, this will only increase the pressure on Mitchell to finally reveal what he did say.