but he's a far weaker character, and won't last as long.

by which time there probably won't be anything of Attlee left

Since they set the cap for a vote of no confidence at some arbitrary level that was basically "even if the Lib Dems leave they still can't bring down the government", Labour + the Liberals would have to contrive some way of passing legislation to remove said arbitrary cap in order to stop Cameron ruling as a minority until 2015.

I don't actually think the Liberals would bring down the coalition anyway. They've gone along with far too much Tory evil to give up now - they're in too deep and the writing is already on the wall. They're going to be demolished at the next election whatever they do, so they may as well continue down their creek without their mode of propulsion.