he winced as the first sensation reminded him of the first time he had spent a whole day in the machine sheds in derby , and struggled to get the taste of iron filings and oil out of his mouth , but then the concentrated caffeine hit raced through his beleaguered bloodstream , which through three years of rationing had been deprived of any genuine sensation of taste or vitality , and he felt alive supercharged , in fact , like one of his railway engines .