It is not difficult to see the things that can go wrong with the Government's latest plan to provide the working population with a pension to top up whatever the state can provide for an increasingly elderly and long-lived populace.

Yet if it really does work, or can be seen to have a decent chance of working, it will be worth the hassle and expense.

To start with, though, the people for whom it is intended - those earning from £5,000 to £35,000 a year in today's money - have got to believe in it. If they don't think they will see a meaningful pension, they will opt out. Face it, some employers may tempt them to do just that with offers of higher pay, bonuses, or whatever.

John Hutton, the Work and Pensions Minister, insists it will "pay to save". He has to. Otherwise his scheme is a waste of every-body's money - if most of the people who pay up for it end up with a pension that simply loses them pound for pound what they would otherwise get in Gordon Brown's pension tax credit, or any means-tested benefit that replaces it.

Mr Hutton can not commit future Chancellors. The best he can do is build a form of words into his Bill shielding contributions in his new personal accounts and the pensions derived from them from all tax or means-test computations. So far he shows no sign of doing that.

Then there is the delicate question of what sort of a pension contributions totalling eight per cent of ordinary pay are likely to buy - the more so for anybody whose working life is interrupted by unemployment, illness, or taking off their best years to have and bring up children.

A final salary scheme seeking to provide a pension of half-pay after 30 years usually costs employer and employee together upwards of 15 per cent.

To achieve half-decent results, Mr Hutton's savings accounts will need to be singularly well invested, with very low costs. Yesterday he spoke of "the option of social, environmental and ethical investments" as well as branded products.

Choice is attractive, but it c osts money. Sin-free investment can work well, though it tends to involve a greater commitment to smallish companies than would be easy with the sort of funds that could flow into Mr Hutton's accounts.

But it cannot come cheap. Nor do most "branded prod-ucts". Tracker funds cost less, but by no means all of them succeed in keeping up with the indices they purport to track. Simplicity can never remove the investment risk. But for this purpose it is the best bet.

The same goes for the administration. Most of the employers involved are going to be quite small. They will never like paying, but it will be least bother if they can just pass the contributions over to the Revenue along with the income tax and and National Insurance.

Result: they will say it is "just an other tax". In a sense it is the Government telling you how to spend your money.