The leader of the opposition's dry tone was completely ignored by the prime minister, who wheeled out a barrel of pre-scripted attack lines about how Miliband "wants to live in a Marxist universe" and "fight some petty socialist campaign".
Marxists are people who believe in the communal ownership of the means of production. Miliband believes in freezing energy prices for 20 months and then increasing competition in the market. He also wants to cancel a cut to corporation tax and pay the revenue to small and medium sized businesses.
You can take issue with plenty of that, but don't call it Marxist. This is not a debate. It's is not a matter of interpretation. No-one with any understanding of basic political concepts believes Miliband is a Marxist or that these are socialist policies. You might as well stuff a pineapple in your mouth and call it chips.
Cameron doesn't believe it either, or else that PPE course at Oxford clearly isn't all its talked up to be. The Tory leader evidently believes the public respond to that sort of scary rhetoric. I'm not so sure about that. For most, I think it probably means nothing. For those who are interested in such things, it will be glaringly inaccurate.
The trouble with what Cameron's doing is that it plays into the modern trolling (original usage) technique whereby any comment remotely to the left is branded Communist, or Islamo-Marxist or whatever strange new conjunction these lunatics have developed since I last checked in on them.
The sight of the prime minister deliberately misusing specific political terms – not fudging, not evading, but deliberately misusing - lowers the standard of debate. It feeds into the type of angry, ignorant rhetoric we get online. It encourages a tribal attacking mentality in political argument which pays scant regard to logic or evidence.
He should be ashamed of using it and embarrassed for the gusto with which he did so.