EMILY GRUNDY, ANN BOWLING, AND MORAG FARQUHAR
In many developed countries the increase in the relative size of the elderly, and more particularly the very old, population has been perceived as an issue presenting major challenges to governments, service providers, and society as a whole ( Pifer and Bronte, 1986; Stolnitz, 1992). Ageing in the individual is associated with declines in the homeostatic mechanisms that bring about adaptive responses to environmental challenges, and all indicators of health status, including service use, show strong associations with age ( Evans, 1988; Grundy, 1991). In England and Wales in 1989/90, for example, per capita public expenditure on health and social services for those aged 85 and over was 15 times as great as expenditure on those aged 15-64, and four-and-a-half times as great as expenditure on 65-74-year-olds ( Robins and Wittenberg, 1992).
Linked with, and to some extent arising from, this concern with the health- care and other costs of age-structure changes, has been a renewed interest in quality of life and social support issues. In England and Wales life expectancy at age 70 increased by some 25 per cent between 1950-2 and 1989 ( OPCS, 1979, 1992). The extent to which these gains have been in 'disability free' rather than 'disabled' years of life remains a matter of fierce debate (for a review see Grundy, 1992a) leading to increased interest in the development of population-based outcome measures such as 'healthy' or 'active' life expectancy ( Robineet al., 1992).
In the social and behavioural gerontological literature recent years have also seen an increased emphasis on concepts such as quality of life and 'successful' or 'positive' ageing ( Baltes and Baltes, 1990). This emphasis, while related to the public-health debate on healthy life expectancy, also reflects a wish by many social gerontologists to challenge what are seen as ageist assumptions that ageing is necessarily a negative experience and elderly people a burden on society.
Demographic and social changes have undoubtedly contributed to both the development and pertinence of these and related debates. From a demographic point of view, not only has the size of the very elderly population been