Here are some of the things Waterhouse knows: the Battle of El Alamein is won, and Montgomery is chasing Rommel westwards across Cyrenaica at what looks like a breakneck pace, driving him back toward the distant Axis stronghold of Tunis. But it’s not the rout it appears to be. If Monty would only grasp the significance of the intelligence coming through the Ultra channel, he would be able to move decisively, to surround and capture large pockets of Germans and Italians. But he never does, and so Rommel stages an orderly retreat, preparing to fight another day, and plodding Monty is roundly cursed in the watch rooms of Bletchley Park for his failure to exploit their priceless but perishable gems of intelligence.