According to recent estimates, the number of people over 60 could rise by 40% in the next 30 years, although there is much dispute about the figures.

In 1995 there were less than 9 million people over 65 in the UK - by 2030 there may be about 13 million.

In 1951, there were 300 people aged 100 and over. By the year 2031, it is estimated that this figure could boom to 36,000.

At the same time, fertility is set to fall as women leave childbirth later and later.

This means there will be fewer young people supporting a growing elderly population.

The ratio of people of working age to people over 65 could fall from 3.7:1 to 2.1:1 in 2040.

With people living longer and longer because of medical and other advances, health experts believe the number of people suffering from debilitating conditions such as cancer and heart disease will grow and could mean a rising demand for nursing care.

The picture is replicated elsewhere in the West, while the developing world is in for an elderly explosion.

In China, it is estimated that the elderly population could double between 2000 and 2027.

Health impact

The World Health Organisation (WHO) warns that the health impact could be enormous.

It predicts a big rise in cancers, coronary heart disease, diabetes, dementia and other illnesses related to ageing.

In the UK, heart expert Professor Michael Marmot has warned that there could be "a huge increase in the number of people suffering from coronary heart disease" in the next century.

Health experts are worried that as people get older, they could become prone to an increasing number of debilitating conditions if they do not keep active.

The WHO has launched a campaign to promote good health in old age.

Doctors in the UK say people have an over-gloomy picture of old age and that there is no reason why they should have a lower quality of life than other people if they keep healthy.

Dr Stephen Webster, a geriatric health expert at Addenbrooke's Hospital in Cambridge, said: "People do have anxiety that there will be a period of disability at the end of their lives.

"But there is no evidence that that is the case if they are encouraged to live a healthy life and this generation of elderly people are in better nick than the previous generation."

Beating the ageing process

He said most of the trouble was due to degenerative problems.

"If they do gentle, regular exercise and keep at a reasonable weight, these can be kept at bay," he said.

"To other people, the elderly may appear to have a fairly restrictive life, but they may have a different view.

"They may develop pleasures in different ways."

Organisations which campaign for the elderly are in favour of policies which support old people to be as independent as possible and allow them more choice and power over their future.

They say cuts in local authority and health budgets mean services like home helps have been "whittled away".

A recent Help the Aged report says: "Without a boost in those services which support independence, there is likely to be increasing pressure on those that cater for dependence: our hospitals, nursing and residential homes."

The organisation wants a national strategy which sets a framework that encourages independence and inclusion.

It says that such a strategy would be much cheaper than putting people into care homes.

Elderly organisations have come together as part of a Millennium Debate of the Age to discuss the various issues related to the ageing population.

They want to see a wider debate on issues such as who funds long-term care, rationing of care - particularly in the light of increasing technological change, and health promotion.

They argue that the present division between social and health services over long-term care is "artificial and damaging".

It means people in places funded by social services have to contribute towards their care costs, whereas those in places funded by the NHS get free care.

In March, the Royal Commission on Long-Term Care for the Elderly, set up by the government, has recommended that all nursing and personal care should be provided free.

However, the government has yet to respond to its main recommendations.