Bush and Blair are men in a hurry, and such men lose wars. If there is a game plan [1a] in Tehran it will be to play Iraq long [1b]. Why stop the Great Satan when he is driving himself to hell in a handcart? If London and Washington really want help in this part of the world they must start from diplomatic ground zero. They will have to stop the holier-than-thou name-calling and the pretence that they hold any cards. They will have to realise that this war has lost them all leverage in the region. They can insult and sanction and threaten. But there is nothing left for them to “do” but leave. They are no longer the subject of that mighty verb, only its painful object.(Pullum’s particular interest in the passage is different from mine, although I agree with his conclusion that “perhaps Simon Jenkins needs a little rest from writing columns to deadline.”)
Let us count the mixed metaphors:
 I have no idea what game it is where the plan might include playing the opponent long; I am familiar with games in which that is a specific tactic applied situationally or against a particular individual player (moving the outfielders out in baseball against a long ball hitter, for example). But I don’t think of such specific tactics as constituting a game plan.
 A handbasket is a vertical conveyance for getting miners down to the working face in a mine; it’s a hand-operated elevator, in other words. One might conceive of descending to hell in one. A handcar is a horizontal conveyance that runs on railroad tracks. It would seem that driving to hell horizontally would make the trip quite a bit longer. A handcart, on the other hand, is something one pushes while walking. One does not drive it.
 Ground zero is the centerpoint of nuclear destruction. One might start from (or with) nothing, but starting from ground zero strikes me as problematic.
 and  Is it an issue if the holier-than-thou are pretending to hold cards in the first place?
 Nothing wrong with the metaphor of a lever, other than its triteness; but mixed with all the others it just adds to the comedy.
My all-time favorite mixed metaphor—stop me if I’ve told you this before—was an ad lib remark by an MIT student guide on a campus tour in the spring of 1963. The day was blustery and raw, and as we entered one of the athletic buildings our guide suggested that we take a break to warm up; he would answer any questions. We were at ground level, at the top of the spectator stands above the pool.
One of the mothers in the group asked whether MIT had guidance counselors. Our guide glanced at the pool, then back toward the woman who had asked the question, a look of sudden literary inspiration in his eyes, and he said, “At MIT no one leads you around by a ring through your nose. You have to sink or swim on your own two feet.”