Correct me if I'm wrong, but didn't KH say the "vast majority" of Christians don't believe in a literal god? He didn't say the "vast majority of UK Christians," he said "Christians." At any rate, this isn't the vast majority at all. Then you look at some of the other questions about other supernatural things and it becomes clear that it's not quite as straight-forward as you're thinking:
71% believe in some sort of resurrection of Jesus with a supernatural element (i.e. not a metaphor for something non-supernatural). That's not quite the same as what I understand KH's beliefs to be where he espouses no supernatural beliefs at all. Moreover, it suggests a somewhat confused view on the respondents' own views as some of them claim not to believe in God, but believe in his son's resurrection.
With this one, it's a similar matter; more than the 54% who believe in God, believe in Heaven. Another conflict.
Now we start getting into the real matter; now we see how the religion actually influences these people's lives and it doesn't appear to be much. I wonder how KH would answer this question.
Even more to the point is how many Christians don't consider themselves religious at all which raises the question of what exactly being a Christian means to them. Which brings us to this:
Only 31-36% actually attempt to follow the religion at all, and the rest are clearly either confused or haven't even really thought about it. KH is not in that group at all; he's clearly thought about his religion a great deal and has very well-defined views on it. If he wants to call himself a Christian, I won't argue with him as it's his choice to define himself as he will. What I will argue is that the numbers of people in this survey who call themselves Christian are not all the same as him in nature, and seem to be more along the lines of basically mindlessly following something they don't really understand.