The book I just created for Cake++ for Linux is much better than the book that you can download for Cake Manchester. Manchester's book is still the same I once created in 6 weeks with a beta of Cake Sans Souci after the computer checkers world championship in Las Vegas in 2002. That book is based on the first 90'000 positions my book generator explored. Now, among these 90'000 moves roughly half will never occur when you set the book to play best moves only. Of the remaining say 50'000 moves, about one quarter are just forced captures. So effectively, that book has a mere 40'000 useful book moves, and they are based on an opening database with "only" 90'000 positions, which means there are also quite a number of errors in that book.
The book for Cake++ only contains lines that Cake will actively select, i.e. there are no wasted moves for lines it will never play. I also left out the forced captures in that book. Finally, all moves are based on the 1'600'000 position opening database, which means that there are only very few errors left (if there are any at all).
Cake Manchester will also get an updated book - I'm just waiting for the book generator to discover the bad move that caused Cake's only loss in the big match between Cake and KingsRow late last year.