" in combat, a pilot had to yank on his control stick with all his strength if he wanted to survive, and stamp his heavy, thick-soled flying boots mercilessly on the rudder pedals with his full weight as if he were kicking somebody on the floor in a life-or-death barroom brawl. In any case, hands and feet were too cold and cramped for gentle movement. The temperature at 25,000 feet was thirty degrees below zero, and the cockpits of the fighters weren’t heated "

― Michael Korda , With Wings Like Eagles: A History of the Battle of Britain