In Britain continuing declines in infant mortality have ensured that life expectancy at birth has consistently improved during this century. Life expectancy in middle ages showed small declines between 1921 and 1940, probably due to real increases in coronary heart disease and cancer mortality which were not counterbalanced by falls in infectious disease mortality of sufficient magnitude. The persistence of social class differentials during this period and the role of diet are discussed. It is suggested that the reversal in the trend in overall mortality seen earlier this century in Britain has implications for recent mortality trends in Eastern Europe.