Andrew Stuttaford, at The National Review Corner, who flagged me on this, makes a couple of good points:

There are two things to remember about this: (1) It was an unpublished analysis [the full text is available here], so it cannot be considered to be Kelly’s final word on this topic (and indeed it wasn’t) and (2) it
could, perhaps, be claimed that it does not directly relate to the immediate public justification for the war that is, of course, the subject of the current controversy in the UK. Nevertheless all this gives further support to those who argue that Tony Blair was acting in good faith.