The PM's loose rhetoric handed Miliband a win as he challenged plans to make 550 Environment Agency Staff redundant.
The coalition made the Labour leader's point for him as it fielded an entirely male frontbench.
The Labour leader broke with his new sober style and hammered Cameron over his refusal to rule out cutting the top tax rate again.
The Labour leader had no convincing riposte to Cameron's claim that he was "an arsonist" who "complains that the fire brigade aren't putting the fires out fast enough".
The "truce" between the two leaders lasted just a week as Cameron declared that Miliband had "all the moral authority of the Reverend Flowers".
The PM's warning that means-testing pensioner benefits would raise only "a very small amount of money" was the most notable moment in a sombre session.
The danger for Miliband is that his "cost-of-living" attack will be blunted as the economic recovery accelerates. Labour must offer a bigger vision.
Rather than following Osborne and denying that living standards are falling, Cameron sought to hold the last Labour government responsible.
Such was the force with which the Deputy PM delivered the Conservatives' attack lines that Peter Bone said he was "turning into a Tory".
The Labour leader accused the Tories of an "intellectual collapse" after their U-turn on payday loans but as Cameron knows, the wise Conservative travels light.