George Osborne's central pitch in yesterday's Budget was that the recovery is strengthening and the economy is coming along nicely, so don't hand back the keys to the people who caused the mess in the first place.

Each of those statements is questionable or wrong, but Labour has boxed itself in by supporting the austerity line all along and now finds it difficult - even if it was so minded - to advocate an alternative expansionary programme when the economy seems to be reviving anyway from the austerity ashes.

Nevertheless Labour should be attacking hard the unsupported optimism of Osborne's predictions across the board. There cannot be a genuine and sustainable recovery without a big revival in business investment, yet it is stuck still at 20 per cent below the pre-crash level - in other words, business itself is still deeply sceptical about the "recovery." Nor can you build a recovery on falling wages - ie on falling demand - and average wages are now 7 per cent down in real terms and still falling.

Rising productivity is another essential component, yet it is one of the lowest in the Organisation for Economic Co-operation and Development and obstinately flat.

And a real recovery can only be built on rising exports closing the balance of payments gap - but exactly the opposite is happening, with the current account deficit rising to £9.5 billion last month.

Even the improved unemployment figures look like being fiddled. There are now over a million people who have been sanctioned - ie had their benefits ended for four weeks or three months because of some alleged infringement of DWP rules - and unless they continue to sign on for jobseeker's allowance, which the vast majority of them understandably do not, they are not included in the unemployment figures.

If they are on a work programme or receiving training or getting universal credit, they similarly "disappear" from the records.

So instead of the jobless total dropping like a stone to near 7 per cent, it is likely that the true figure is stuck much closer to 7.5 per cent or even 8 per cent.

And even where new jobs have been created, 80 per cent of them are low-paid at little more than the minimum wage and many are on zero-hours contracts.

Then there's the problem that this so-called recovery is heavily dependent on consumer borrowing.

That may stimulate growth for a little while, but it cannot be sustained for long while real-terms wage slippage continues, as it does.

There is far too much financial froth about this upturn, with stockmarkets approaching all-time highs while the all-important manufacturing base remains stagnant, unhelped by a strongly rising exchange rate.

On these foundations it's difficult to see enough substance to justify predictions of 2.5 per cent growth this year and 3 per cent next.

We should remember that Treasury and Office for Budget Responsibility predictions in the past have been grossly exaggerated time and time again.

That's enough for Labour to get its teeth into, and even at this stage to press for a much more expansionist policy as a far better way than austerity to cut the deficit.