However much Ed Miliband wanted to ask him about Egypt and primary school places, there was only one subject David Cameron wanted to talk about at today's PMQs: Labour's relationship with Unite and the Falkirk selection row. "His questions are written by Len McCluskey," he declared, apropos of nothing, after Miliband asked him why a third of new schools were being built in areas with surplus places. At least 13 references to Unite and McCluskey followed as Cameron branded Miliband "too weak to run Labour and certainly too weak to run the country".
It earned him the best reception he's had all year from Tory backbenchers, although Miliband returned fire with as much passion as we've seen from him. This was a PM, he declared, "who had dinners for donors in Downing Street, gave tax cuts to his Christmas card list and brought Andy Coulson into Downing Street. Lecturing us about ethics takes double standards to a whole new level." But since the Labour leader's only response was to change the subject, the spoils went to Cameron.
At that point, his pre-planned attack lines delivered, the PM would have been wise to move on. But Cameron couldn't help himself. In reponse to a question from the well-regarded Labour MP Stephen Timms on how demand for foodbanks had risen from 30,00 households before the election to 350,000, Cameron blustered: "I'm sure as a member of Unite, the Honourable Member will want to look very carefully at his own constituency party - who knows how many people they've bought and put on the register". It was a frivolous response to a sincere question.
One can hardly blame the Tories for seeking to take advantage of the Falkirk debacle but they shouldn't make the error of assuming that voters share their instinctive loathing of the trade unions. A recent Populus poll found that 69 per cent of the public agree that "it is important that Labour retains its strong links with the Trade Unions because they represent many hard working people in Britain", including 53 per cent of Tory voters, with just 28 per cent disagreeing. The response of most people to the allegation that Unite manipulated the Falkirk selection process by signing up trade unionists as Labour members without their permission is likely to be one of indifference.
The days when Ted Heath was forced to call an election to find out whether it was he or the unions "who ran Britain" (answer: the unions) are long gone. Today, the unions present a far less threatening face. If he wants to win converts, rather than merely rouse supporters, Cameron would be wise to avoid a repeat of today's monomania.