Note: the pics used in this review - aside from the cover - are not from the book!
 Flak was very inaccurate and inefficient, and could cause 'collateral damage' when spent munitions or unexploded rounds returned to earth. But it had psychological value in helping people feel they were being defended, and it unnerved attacking aircraft, making their job harder.
 I like this picture for several reasons, two of which are: my grandfather was a Canadian servicemen, over here during (and after!) WWII; Duxford is local to me, and I've been there many, many times. The text describing this image at Wikipedia says: 'Three decorated fighter pilots of No. 242 (Canadian) Squadron RAF, standing outside the Officers' Mess at Duxford, Cambridgeshire. They are (left to right): Pilot Officer W L McKnight, Acting Squadron Leader D R S Bader (Commanding Officer), and Acting Flight Lieutenant G E Ball. By the date this photograph was taken these pilots had, between them, shot down over thirty enemy aircraft.'
 This pic is from 1942, after the Battle of Britain, but it gets the idea across!