What would have happened if a German invasion had gone ahead in 1940? It doesn’t bear thinking about, does it. But Richard Cox does get us thinking. He launches a full-frontal assault on our imaginations by expanding on the results from a war game, held at Sandhurst’s Staff College, in 1974. By examining the teams’ conclusions on Hitler’s plans for Operation SEALION – its weaknesses and its strengths – he has us reviewing what we thought we knew about the battle for the skies, and thinking again about what might have been if the Fuhrer had advanced across the English Channel.