Isn't is reasonable to hold the leader of your country at least "partly" to blame if the country is attacked by terrorists?
To say the leader is completely blameless, is to say that there is absolutely nothing a country can do to protect itself from terrorist attacks. But we obviously believe there ARE things we can do, or else we wouldn't spend billions of dollars trying.
A large majority in the poll found Blair either blameless, or only marginally to blame. That looks like a reasonable and good thing.
I guess I'm taking a different definition of "blame".
BTW, I am close to being of the opinion that there ISN'T much the leadership can do to stop things like this, so I would have been part of the 1/3 who said he was blameless.