A recurring theme in the old Peanuts cartoon strip was Charlie Brown approaching a football placed for him by Lucy. At the last minute, each time, she takes it away, leaving him flat on his back. The cartoonist was not trying to describe new Labour's repeated promises to reform the benefits system. But he might as well have been.

James Purnell, the Work and Pensions Secretary, is the latest to promise reform (see page 17). His Green Paper proposals may well come to merit the “revolutionary” label he has given them: but only if a government that has been decidedly half-hearted about welfare reform is now ready to see through some radical changes.

Change is sorely needed. There are 4.5 million people claiming unemployment or incapacity benefit. It is quite wrong that the number of people claiming incapacity benefit has remained static in the past ten years, at a time of unprecedented economic growth. It is shocking that only half a million unemployed adults have found work during a period when three million new jobs were created. That is a cruel waste of lives and potential. Apart from those whose physical disabilities make it genuinely impossible for them to work, many long-term claimants become crippled with depression. Those who receive incapacity benefit for more than six months remain on it for an average of eighteen years, until they retire or die.

Similar problems have been successfully tackled in different parts of the US with programmes that couple strong incentives for people to work with comprehensive support before and after they find a job. America Works, an agency that operates in New York and California, boasts that 80 per cent of its clients have stayed in work for three years. That is in stark contrast to the UK's New Deal programme, where 40 per cent of those getting a job have reappeared on the dole within six months.

Mr Purnell cites the US as an important influence. He has understood the need for long-term support from back-to-work agencies, and is ready to eliminate the absurd bias against the private sector. His proposals are tough. First, drug addicts who refuse treatment will lose benefits. Secondly, anyone who has not worked for two years will have to take full-time “community work”, such as clearing litter and graffiti. This stops short of the Wisconsin system, where families face a lifetime limit on benefits, and of the New York system where claimants are expected to spend 30 hours a week in “employment-related activity”. But it will make it much harder for people to claim benefit while working on the black market.

The timing is tricky. In an economic downturn, it is not clear where the extra jobs will come from. That is not a reason to hold back: it simply means that Mr Purnell is being impressively brave. But he should consider adopting the America Works tactic of initially keeping workers on the agency's payroll, not the employers', to reduce employers' hiring risk. He should also take seriously Frank Field's concerns (see page 24) that some claimants may still be able to game the new system, spurred on by the offer of higher allowances for the genuinely disabled.

The Green Paper heralds a welcome return to William Beveridge's principle of co-operation between the State and the individual, with neither abusing the other. But whether a new era has really dawned depends partly on how long Mr Purnell stays in the job, since many of his colleagues seem less convinced about the merits of “tough love”. He is right to take them on.

Now he will have to battle hard to make sure his proposals are not destroyed by dozens of small amendments. He will need Gordon Brown's help to prevent the welfare reform ball being snatched away once again.