Last week Gordon Brown started his press conference with the announcement that he intended to be entirely candid. Perhaps he will start his next conference by prefacing all his remarks with the words “with the greatest of respect”. For there could hardly be a more depressing departure from candour than the statements the Prime Minister has made this week on public spending.

His attempt in the House of Commons to suggest that Labour is the party of investment and the Conservatives are the party of cuts is wilfully misleading and archly political. And with a more assured comic touch than he usually manages for his jokes the Prime Minister has not only created a false dividing line, he has put himself on the wrong side of it.

The figures could not be clearer. If Labour stayed in office beyond the next election it would be cutting spending at around 7 per cent a year. Any Conservative who talks of large cuts is therefore talking of something that any party will have to do after the next election. The only way of making the cuts less severe would be to start earlier, something Mr Brown has refused to do.

There exists, therefore, a great inconsistency and large irony. The Chancellor, keen to propitiate the markets, emphasises how prudent the Government is being now, and how tough on spending. The Prime Minister, keen to dish the Tories, talks of investment and lavish spending. And the irony? They are both wrong. The Government is not being as prudent, and the talk of investment in the future is delusional.

Yet even if the distinction that Mr Brown was trying to make were not a figment of his imagination, what makes him believe that when asked to choose between investment and cuts, people will choose investment?

The very word “investment” itself has become extremely tiresome. What was tolerable in the early days of new Labour has, like a lot of things, begun to sound faintly ridiculous. Does the Prime Minister suppose that people have not worked out by now that investment is another word for public spending and public spending another word for tax rises? And if people really did look at spending as an investment, does Mr Brown suppose that people will think that it has been a good one?

Many people feel now that they might have been better putting their savings into Enron shares than in one of Mr Brown’s “investments” — with a better return and a bigger chance of discovering what happened to the money. Perhaps the Prime Minister might care to reflect on the report of the Office for National Statistics (ONS) this week. Between 1997 and 2007, productivity in the public sector fell by 3.2 per cent, at a time when productivity in the wider economy rose between 2 per cent and 2.5 per cent a year. Care to “invest” some more, anyone?

Let us take up Mr Brown’s invitation to be candid. Having carried on increasing public spending during a boom, this country now has a major fiscal crisis. It needs a government and a prime minister that understand this. A successful government would accept reality and begin to deal with it. It would start now to articulate how it would reduce levels of public spending in a way that protects, as far as possible, services that people rely on, particularly vulnerable people. The debate we should be having in the run-up to the next election should be about who has the best ideas for reshaping services and reducing what government does.

David Cameron should not be afraid to acknowledge that he will make cuts, for that is what the economic situation demands. If Mr Brown attempts to fight the election on investment versus cuts, he will find that instead he is fighting on fantasy versus truth.