The Spectator nearly a month ago had a review of this tome (at 960 pgs.), which I overlooked till now. The author is Halik Kochanski (who has appeared as an author of two books in 2015 threads). This bookseller - there are others - has fuller details and reviews: https://www.amazon.co.uk/Resistance-Underground-War-Europe-1939-1945/dp/0241004284
