All the talk in markets is of a possible slowdown in the rate of decline.

The reason why share prices around the world have been rising in the past few days is not that there is evidence of economic recovery - but rather that the pace of deterioration may have been decelerating.

Think of it as what happens when you touch down in a plane and the pilot turns on the thrust reversers at full pelt - the plane stops before it overshoots the runway (barring mechanical failure).

The pilots of the global economy have been gradually increasing the force (and noise) of thrust-reversal in recent months: monetary and fiscal authorities have cut the cost of credit, pumped money into the system, rebuilt banks' balance sheets and stimulated the economy.

That amounts to many trillions of dollars of economic force. There may be more to do - but it's bound to have an effect.

Now, since it was a collapse in the availability of credit that pushed the world into the worst economic conditions since the 1930s, an improvement in the supply of credit would be (for most people) an encouraging sign.

In that context, the Bank of England's last credit conditions survey - which was published on Thursday but was drowned out by G20 mania - may turn out to be significant.

The survey claimed that in the first quarter of this year there had been a slight increase in the availability of loans to companies and a less-than-expected reduction in the supply of unsecured credit to households and small businesses - although the supply of mortgages shrank again.

Perhaps more relevantly, credit conditions were expected to improve in the coming three months: credit will remain tight, but not quite as tight as it has been.

It could be the first cuckoo (sorry for mixing my metaphors).

And there may be other cuckoo-ish noises; there's been contradictory data on what's happening in the housing market in the UK - whose underlying message may be that prices aren't dropping as quickly as they were - and a less-than-expected fall in US motorcar sales (though today's news on car sales in Britain is dismal).

I am being parochial, and economic stats from around the world remain pretty dire.

But here's the paradox. It's impossible to prove that we've heard the first cuckoo in spring. However that may not be the disaster it seems. What matters - to an extent - is what investors think they've heard.

Confused?

The point - which I've been making for some time - is that there is an inextricable link between asset prices and the supply of credit (and between the supply of credit and economic prospects in general). Or to put it another way, a pre-condition of economic recovery is that asset prices have to stabilise and then rise in a sustained way.

For asset prices to rise, investors' appetite for risk has to increase - which would happen as and when they see portents of better times ahead. And if - for example - property prices then bounced even a little, banks would have a bit more confidence when lending, because collateral would not be seen as inexorably shrinking.

A similar virtuous process stems from a generalised rise in share prices. And that's a trend we have been seeing from Tokyo to Wall Street to London.

If share prices rise, including the share prices of banks (as has been happening), then it becomes much more of a realistic prospect for companies - including banks - to raise the equity capital they need.

That in turn both reduces the demand for emergency lines of credit and increases the willingness of banks to lend.

Against that background, the strong demand for HSBC's £12.5bn of new shares has to be seen as a very good thing.

None of which is to say that even if we've heard the cuckoo that it couldn't yet be wiped out by yet another malevolent storm.

And I've bored you rigid with my fears about the huge challenges we'll face, even after the recession has ended in a technical sense.

That said, it would be mean-spirited not to take pleasure from the thought that we might have heard a cuckoo.

