Re: Sadly missed
From Wikipedia and other sources, it appears that the book completed last year is called The Shepherd's Crown and is part (the last) of the Tiffany Aching arc of books. (Publication date seems to be July, or autumn, 2015.) These books are set in the Discworld and were intended for a 'young adult' audience. Personally, as a quite old adult, I found 'I Shall Wear Midnight' to be a very mature story, wonderfully told.
I'll be buying it as soon as it becomes available.