The death of David Kelly - Where did the gaffer tape story originate?

The knife found beside David Kelly's body reportedly had no recoverable fingerprints.

One story that is doing the rounds is that the knife was covered with gaffer tape and (so the story goes) it is difficult or impossible to recover fingerprints from gaffer tape.

One question that occurred to me is where did the gaffer tape story originate?

I could find no mention of gaffer tape on the Hutton Inquiry web site.

The earliest mention of gaffer tape supposedly on the knife that I can find is from 4th July 2010 in a comment here from Tom Mangold.

Mangold wrote:

The pruning knife used by David to cut his wrist was covered in gaffer-tape, as are many knives, to prevent the fingers slipping on to the blade and provide a firmer grip. It is almost impossible to retrieve finger prints from this kind of material. For what its worth, I believe that had the government allowed a normal inquest to take place then the fruit-cake theories would never have gained traction.

Shortly thereafter other journalists, Andrew Gilligan being one example, pick up the story, David Kelly was not murdered:

The absence of fingerprints on the knife may be explained by the fact that the knife handle was reportedly covered in gaffer tape, which does not easily hold fingerprints, or by the fact that it spent the night in the open. Importantly, the knife itself was one that David kept in his study and which had belonged to him from boyhood.

And, inevitably, the gaffer tape story echoes on round the Internet.

Is this 4th July 2010 mention of gaffer tape by Tom Mangold the first mention of the supposed story?

And is it true that gaffer tape doesn't hold fingerprints?