After writing the previous post, I found I had an email from Peter J. Tyldesley, the owner of the diary damaged at the British Library. He's launched a website about the case, at which he claims the book was never in fact at the BL to be rebound, but was deposited there for safekeeping. There's much more there at the website which I'm still reading through myself, but I did want to get it out as soon as I could.
Curious and curiouser, indeed.
