I don't think the Tories would win. Remember the Brown Bounce, everyone. Labour's majority would be reduced to 30-40. Cameron's momentum would stall, but his party would stick with him, as they are committed to the project.
This was at the height of Ming Campbell being isolated and attacked, though. Potentially the Lib Dems could pick up a protest vote and perform quite well, which might shut up Ming's critics for a while.
Assuming the fusillade of disasters happens like OTL, the 2007 election would probably be remembered like the 1992 one - a poisoned chalice.