Could child benefit be Cameron's poll tax?

I've just caught up with the first PMQs duel between Cameron and Miliband, and it was startling to see just how easily the new Labour leader was allowed to score a hit on the issue of families with only one working parent being effectively discriminated against as a result of the threshold for the withdrawal of child benefit. Miliband's jibe that the Prime Minister "had no defence" was quite literally true. That marks a change, though, because the government did have a defence on the day the policy was announced - Philip Hammond breezily accepted on Newsnight that there would be a little "rough justice", but insisted that was unavoidable if the costs and complications of full-scale means-testing were to be avoided. It seems the penny has dropped that this wasn't such a winning line - but the fact that they haven't been able to come up with anything better in the intervening week is extremely telling. Cameron instead rather lamely answered the question he wished he'd been asked, and defended the general principle of withdrawing benefits from the wealthy.

In truth, of course, this isn't "a little" rough justice - as Miliband noted, there will be hundreds of thousands of families with a single working parent who lose out. And presumably as relative high-earners, these people are also to a significant extent natural Tory supporters. It starts to beg the question - could the controversy over the changes to child benefit be a slow-burner that eventually turns into Cameron's "poll tax"? After all, the poll tax was also a system that permitted lots of rough justice in the pursuit of maximum "simplicity". The Tories really should have learned their lesson by now - in any battle for public support between "simplicity" and "fairness", there will only ever be one winner.

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Later in PMQs, Angus MacNeil spoke very eloquently on behalf on his constituents, the family of Linda Norgrove. Can we now expect some more ill-judged musings from Fraser Nelson on the subject of a Scottish politician getting above his station?