Sooner or later everybody has to think about old age, and even if it took Gordon Brown 11 years in high office to get round to the subject, that he did so yesterday is to be welcomed. His announcement, made jointly with the Secretary of State for Health, Alan Johnson, of a “national debate on the future of care and support” is belated but a start at least.

The statistical trends have been clear for years. There are just under five million Britons aged 75 and over. Thanks to improved sanitation and housing, better diets and access to medicine, this number will increase by more than two thirds over the next quarter of a century. The number of people aged 85 and over will quadruple to about five million in the same period. Meanwhile, the roll call of centenarians in England and Wales will rise from 10,000 to 40,000 by 2031, according to the Office for National Statistics.

It is good that people are living longer. It is bad that the Government has appeared so unwilling to make adequate preparations for this development. If care for the elderly is maintained at current levels, the annual cost to taxpayers will triple, rising from £12.7 billion at present to £40.9 billion, in today's prices, by 2041. Inflation means the actual cost could exceed £100 billion a year - the same as the total amount spent on the NHS at present. Unchecked, the cost could become too great for the State to bear. Yet as leaders of a society that purports to be civilised, the Government has a moral obligation to ensure that people can move through their final years in safety, dignity and comfort.

Ministers must ensure that the long-term nursing care given to old people meets acceptable standards. Ministers must also decide how much support should be given by the State, funded by taxpayers, and how much should be left for individuals to sort out for themselves. Here lies the knottiest problem. If the State is too generous, people will have no incentive to provide for their own care, and the cost to the State will balloon. If the State is too parsimonious, unwise or unlucky pensioners will be left on the uncivilised margins of society.

A safety net for those that cannot, or do not, plan ahead is required. It must be sound, but basic enough to ensure that pensioners have an incentive to want more and be prepared to pay for extras. Means testing may be inevitable but the current framework should be reviewed. Under current rules, state assistance is withdrawn if a pensioner has more than £22,250 in savings, including property. A complex array of tapering benefits are paid to those with less than £22,250 where greater simplicity is advisable. Overall, too little reward goes to those thrifty individuals who try to help themselves.

Reform should take full account of the support provided by friends, family and other voluntary organisations. It should give full credit to these unpaid heroes and heroines. A workable system of care for the elderly should also encourage the private sector and the kind of competition that enhances choice, the provision of high-quality services and keen prices.

With this issue, Gordon Brown has an opportunity to show he is a politician of substance who genuinely cares about the long-term welfare of citizens. There may be few short-term political gains to be made from finding a truly serious answer to the questions he is addressing. But for a serious politician like Mr Brown, success would be a worthy achievement.