Whether Jeremy directly or indirectly arranged for Harrison to get the threatening letter, no one knows. But why should Jeremy a supporter or supporters be so upset or surprised if a new book is going to highlight guilt ?
Supporters on forums have often mentioned Mason Doyle's forthcoming book. Which seems to have disappeared. Optimistically believing that a new book will bring up new evidence showing Jeremy's innocence. But if that was going to happen, surely Jeremy would have already found this evidence. He's been campaigning for 29 years, & apparently has two sets of legal teams and a campaign team.
The best a new book could do would be to be a Scott Lomax esq book. Which would in a biased way suggest his innocence.
Any good investigative author will try to produce a balanced book, which would highlight the guilt that has convicted Jeremy for 29 years. While discussing the unproven claims about police corruption, family frame ups & savage girlfriends.
So why would Jeremy, a supporter or supporters be so upset when finding out the content of Harrison's book ?
One reason is because Harrison went into the book believing there could be a miscarriage of justice. Which could be a reason why Jeremy has engaged with him. However, similar to other writers Harrison has changed stance.
Being the first book in years, a guilty book will be a big blow which negates the internet and media work trying to secure a release. Obviously too much of a big blow for someone, or some people.
Writing a threatening letter does more harm than good. It will never stop the author trying to get the book published. He may have spent years writing it. It creates bad publicity and highlights that an author believes Jeremy is guilty, putting Jeremy & his supporters in a bad light.
Why do people believe a person or people wrote the threatening letter ?