At the last census in 1966 there were nearly 12 million people aged between 45 and 64 in England and Wales. This age group, which for convenience will be termed 'middle age' throughout this paper, covers the second part of economically active life. It is a time during which, while many careers are still reaching a peak, a decline in physical and mental powers has already begun to set in. As middle age is entered, a new phase of life begins. Patterns of morbidity and mortality rapidly alter as degenerative diseases become increasingly more significant.