The 'Third Agers' of tomorrow, now in their forties, represent a 'decisive break with the past', says Leisure Futures, from the Henley Centre, the forecasting group. Unlike preceding generations, whose upbringing gave them a more frugal outlook, they were socialised in the 1960s, 'a decade of expanding individual choices and apparently inherent economic growth'.
The rise of a relatively affluent and leisured Third Age, combined with demographic changes that are producing fewer young people, will gradually shift the cultural centre of gravity from youth to age, the study says.
By 2031, the proportion of the UK population over 50 - 28 per cent in 1951 and 32 per cent in 1991 - will be 38 per cent. The study quotes Peter Laslett, the historian and demographer: 'Europe and the West are growing older and will never be young again.'
Among the implications are a rise in 'grey power'. This has already happened in the US, where the postwar baby boom took place a decade earlier than in the UK and groups such as the American Association of Retired People have 37 million members and represent a powerful lobby - and important new markets for leisure and education.
Although the leisured Third Agers will still probably represent only a minority of those aged between 50 and 75, such 'dynamic' consumers 'should already be the most sought-after target' for the leisure industry, the study says.
Time-use studies by Henley show that Third Age consumers already take part more widely in active leisure pursuits, such as long country walks, short-break holidays and visits to museums or historic buildings, than younger people and are 'catching' their juniors in terms of playing team sports, swimming and visits to sports centres, evening classes and cinemas. Participation rates for those aged 45 to 59 have risen sharply since 1986.
Retirement is viewed less and less as a 'form of renunciation', says the study. Changes in work patterns also suggest that retirement for many people 'will no longer be characterised by feelings of redundancy and apathy and long periods of inactivity spent watching television'.
Chief among these is the dramatic decline in employment of men aged over 55 in the past 20 years, because of early retirement or redundancy. This will bring an end to the 'male' concept of leisure - which assumes a clear stage of work followed by one of rest - and a move to a 'female' model, with more varied lifestyles and a less rigid division of work and leisure.
Richard Woods, editor of Leisure Futures, said the 'disproportionate influence' wielded by the baby-boom generation seemed likely to continue, with individuals such as Germaine Greer and Betty Friedan continuing to defend their 'generational cohort'.
Recession and the spread of higher education meant that young people had less money. Coupled with demographic factors, this made a return to the youth culture of the 1960s and 1970s unlikely. However, Mr Woods said the worsening 'dependency ratio' - the balance between younger people in employment and older people on pensions or benefits - would eventually lead to a higher retirement age.
Leisure Futures, Vol 1, 1994; Henley Centre, 9 Bridewell Place, London EC4V 6AY; by subscription.