It is some time since David Cameron has endured a defeat as bad as that he suffered at today's PMQs. Ed Miliband unsurprisingly led on the lobbying scandal and pressed the case for reform of MPs' second jobs (the subject of a Labour motion tonight). Cameron replied that he did not rule out "further changes" but the tone of lofty scepticism was unmistakable. At this, an animated Miliband pounced. Had the PM not once declared that "double-jobbing MPs won’t get a look-in when I’m in charge"? Cameron replied with what he thought was a trump card - Labour's motion would allow MPs to serve as paid trade union officials - but it proved to be a dud. Miliband simply ruled out this exemption and invited the PM to do business. (There are, in any case, no Labour MPs who occupy this role.) He offered to consult on the level of an outside earnings cap, while demanding that the government agree to a ban on directorships and consultancies.

A wrong-footed Cameron could only respond with pre-heated attacks on the trade unions, intermingled with cheap barbs at Tristram Hunt and David Miliband over their outside earnings. (The most reliable indicator of a defeat for the PM is the number of times he mentions Len McCluskey and co.) Swatting away the case for reform, he appeared as inert as Gordon Brown did following the expenses scandal. "This is a very big test. You can vote for two jobs, or you can vote for one. I’ll be voting for one job; what will he be voting for?" cried Miliband with the confidence of a man who knows he has the public on his side (voters support a ban on MPs holding second jobs by 56 per cent to 25). In return, Cameron could only offer feeble non sequiturs: "I make an offer to him, no more support from trade unions for the Labour Party – then we’ve got a deal!" He looked like what he was: a man desperate to change the subject.

Following his exchanges with Miliband, Cameron was questioned by the DUP's Westminster leader Nigel Dodds on the seemingly doomed TV debates. Today's session was an apt reminder of why he does not want to face the leader of the opposition.