Calculations can be made to show the financial gains to voters of average age successfully voting to increase pensions, and there is much impressive academic work in this field, especially emanating from continental Europe. Serious cross-national research has shown that for every year by which the average age of voters increases, government spending on pensions increases by 0.5 per cent of GDP. This would translate into an increase in pension spending of £45.5bn per annum in the UK over the next 30 years (at today's prices).

This problem of an ageing population is not, of course, confined to the UK. In many continental European countries the trend is even starker.

In New Zealand the proportion will level off at about 42 per cent. But in Germany and Italy the proportion of people over the age of 55 will be more than 50 per cent in less than 15 years. Average retirement ages are lower in most continental European countries. Even without making any allowance for differential turnout, the majority of the electorate in most of Europe will be retired or close to retirement within a few years. The total proportion of voters who are economically inactive (due to unemployment, education, disability or choice) will, of course, be much greater. Bosnia-Herzegovina faces special circumstances - high levels of outward migration. But this is quite common in Central and Eastern European countries. The lopsided nature of their demographic profile is very worrying indeed.

A perfect storm is brewing. Europe desperately needs pension reform. But who is going to vote for it? Are turkeys going to vote for Christmas? The evidence from many countries is clear. As the population ages, older people use the ballot box to transfer resources to themselves from the younger generation - and it is happening already in the UK. The outlook will be very difficult for any party that wants to reduce public spending in general and it will be even harder for parties to resist transferring economic resources to the old.